Enlightenment Ideals and Progress in Science, Religion

 The sources detail a sophisticated research context and methodology centered on empirically testing the cultural shifts associated with Enlightenment ideals that preceded the British Industrial Revolution (1500–1900). The core objective is to trace the evolution of language concerning science, religion, and political economy to determine if a progress-oriented culture associated with science and industry manifested in British printed works.

Research Context: Enlightenment Ideals and Belief in Progress

The research builds primarily upon the influential argument put forth by Joel Mokyr (2016), who posits that a progress-oriented view of science, championed by Enlightenment thinkers like Francis Bacon and Isaac Newton, was central to the emergence of the "Industrial Enlightenment" and, eventually, Britain's Industrial Revolution. This cultural shift involved the nascent and revolutionary idea that scientific understanding could be utilized to improve the condition of humankind.

The study addresses two key gaps in existing evidence regarding this theory:

1. Diffusion of Ideas: While elite thinkers held progress-oriented views, it was unclear if these ideas diffused to the broader corpus of written materials accessible to the artisans and craftsmen who drove industrialization.
2. Quantitative Validation: The necessity for quantitative evidence to complement qualitative studies of the hundreds of thousands of works produced during this period.

The findings resulting from this research context and methodology yield three main conclusions relevant to the Enlightenment ideals:

1. Secularization of Science: A quantitative separation in the languages of science and religion began in the mid-18th century, indicating that the secularization of science became entrenched during the Enlightenment.
2. Applied Science and Progress: Volumes using language at the nexus of science and political economy became measurably more progress-oriented during the Enlightenment period. Critically, works using the language of "pure" science were largely neutral regarding progress-oriented language.
3. Industrial Alignment: Volumes employing industrial language—especially those located at the science-political economy nexus—were more progress-oriented starting in the 18th century. This strongly supports the "Industrial Enlightenment" hypothesis, suggesting that progress-oriented views were imbued in practical, industrial volumes aimed at both scientific and non-scientific audiences with political or economic interests.

Research Methodology

The methodology relies heavily on large-scale textual analysis and computational techniques, treating "words as data".

1. Data Collection and Preparation

The data corpus consists of 264,443 unique volumes published in England and written in English between 1500 and 1900, gathered from the Hathitrust Digital Library (HDL). This includes a wide array of works, such as fiction, scientific manuals, and religious texts.

• Data Model: Each volume is modeled as a "bag of words," meaning the analysis considers the frequency of words within a document, disregarding their order.
• Cleaning and Standardization: The data underwent extensive cleaning, including removing duplicates, correcting Optical Character Recognition (OCR) errors, standardizing historical spellings (e.g., using the Morph Adorner algorithm), and removing common "stop words" and short words. Specific words with relevant double meanings (like 'sin') were manually eliminated to prevent false connections between categories.

2. Topic Modeling and Categorization

To objectively identify latent thematic structures, the study utilized Latent Dirichlet Allocation (LDA), an unsupervised machine learning algorithm.

• Topic Generation: The LDA extracted 60 latent topics based on words that commonly co-occurred within the same volume. Model quality was determined by minimizing the perplexity measure using cross-validation.
• Categorization: An algorithm was applied to determine sets of topics that most frequently co-existed. Based on their relative importance and distinctness, the topics were grouped into three broad categories: science, religion, and political economy. Importantly, the volumes were classified based on the language they employed, not solely their traditional subject matter (e.g., a scientific work might use religious language).
• Volume Weights: Time-varying categorical weights ($\beta_{t,c}$) were derived for all 60 topics, and subsequently, for each individual volume, reflecting the proportional usage of language related to science, religion, and political economy within that work.

3. Sentiment and Industrial Measurement

Progress-Oriented Sentiment

To test Mokyr's hypothesis regarding progress, a "progress-oriented sentiment" score was calculated for each volume.

• Dictionary Development: A dictionary of progress-oriented words was compiled from thesauruses and refined manually. Words were removed if they were associated with movement (e.g., 'journey'), had alternative meanings in science (e.g., 'evolution' or 'momentum'), or were not in use prior to 1643 (the year of Isaac Newton’s birth) to avoid biasing results toward later periods of the Enlightenment.
• Scoring: The score was calculated as the total count of progress-oriented words in a volume, normalized by the total word count. Robustness checks used alternative dictionaries, including those derived from the 1708 Dictionarium Anglo-Britannicum.

Industrial Score

To specifically test the "Industrial Enlightenment" hypothesis, an "industrial score" was developed.

• Dictionary Source: The industrial word list was created by transcribing the detailed indices of five volumes of Appleby’s Illustrated Handbook of Machinery (1877–1903). This late 19th-century source covers industrial machinery, engines, mining, and railways.
• Scoring: Each industrial word was weighted by its frequency in the handbooks' indices, and this list was used to score every volume in the corpus, normalized by volume length. Robustness checks confirmed similar results using industrial words verified to be in use in 1708.

4. Quantitative Analysis

The final step utilized regression analysis (Ordinary Least Squares) to quantify the correlation between progress-oriented sentiment, the language categories (science, religion, political economy), and the industrial score, incorporating time fixed effects and interactions. This analysis was framed as an "accounting exercise" to clarify the historical correlation, not to imply causation, given the potential for omitted variable bias or reverse causation.

The methodology was also applied to specific subsets, such as manuals (works intended to convey practical instructions), providing further support that it was works of applied science ("Industrial Enlightenment") that became the most progress-oriented prior to and during industrialization.

This rigorous methodology provides quantitative support for the cultural transformation—the rise of a specific, pragmatic, and secular belief in progress—that underpinned the massive economic changes of 18th and 19th-century Britain.

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Analogy to solidify understanding: The methodology used here is like taking a vast, cluttered library (the 264,443 volumes) and running an invisible, algorithmic sorting machine (LDA) over it. Instead of just noting whether a book is about "Science" or "Religion" (which are often mixed), the machine measures the flavor of the language used (the category weights). It then uses two different historical ingredient lists—one for "Progress" and one for "Industry"—to see which flavored books used those specific ingredients the most, revealing that the books blending scientific and economic language were the main carriers of the new progress-oriented ideas that fueled the Industrial Revolution.

The sources establish the British Industrial Revolution as the central historical episode being investigated, framing the entire research context and dictating the specific methodology employed. The study uses textual analysis to explore the cultural shifts that are hypothesized to have enabled this massive economic transformation (1500–1900).

Focus on the British Industrial Revolution

The primary focus of the research is on understanding the cultural values that led to Britain's industrialization. This investigation is motivated by the prominent argument put forth by economist Joel Mokyr (2016), who links a nascent, progress-oriented view of science held by Enlightenment thinkers (like Francis Bacon and Isaac Newton) to the emergence of the "Industrial Enlightenment" and, ultimately, the Industrial Revolution in Britain.

Core Hypotheses Related to Industrialization

The research specifically targets two gaps in the existing, primarily qualitative, evidence regarding the Industrial Revolution's cultural roots:

1. Diffusion of Progress: The study tests whether progress-oriented ideas diffused beyond elite thinkers to the broader corpus of written materials accessible to the skilled artisans and craftsmen who were the driving force of Britain’s Industrial Revolution. The "Industrial Enlightenment" was largely advanced by these individuals, suggesting that works using the languages of science and industry should also have used progress-oriented language.
2. Industrial Alignment: A more specific implication derived from Mokyr's thesis is tested: that works associated with industrialization (volumes employing industrial language) became measurably more progress-oriented during the Enlightenment period.

Key Findings Regarding Industrialization

The study's quantitative findings directly support the "Industrial Enlightenment" hypothesis regarding Britain's economic takeoff:

• Science-Political Economy Nexus: The most progress-oriented works were found at the nexus of the languages of science and political economy (or economics or law). This indicates that volumes that used the language of applied science were the key carriers of progress-oriented views.
• Industrial Language and Progress: Volumes with higher industrial scores became measurably more progress-oriented starting in the 18th century. This correlation suggests that progress-oriented views were specifically imbued in the pragmatic, industrial volumes that reached both scientific and non-scientific audiences with economic interests.
• Timing: The language of applied science began to become more progress-oriented in the mid-18th century, aligning with the commencement of Britain's industrialization and consistent with the timing of Mokyr's hypothesis.

Methodology in the Context of the Industrial Revolution Focus

The methodology was explicitly designed to address the cultural change preceding the British Industrial Revolution by treating "words as data".

1. Data Corpus

The core data consists of 264,443 unique volumes printed in England and written in English between 1500 and 1900. This specific timeframe (leading up to and through the Industrial Revolution) and geography (England/Britain) were chosen to trace the evolution of cultural attitudes relevant to Britain's industrialization. The corpus includes a wide array of works, such as scientific manuals and religious texts, allowing the researchers to determine what ideas were "available to those artisans and craftsmen" who drove the Industrial Revolution.

2. Measuring Industrial Content

A critical methodological component tailored to the Industrial Revolution focus was the development of the "industrial score".

• Dictionary Source: The dictionary of industrial words was transcribed from the detailed indices of five volumes of Appleby’s Illustrated Handbook of Machinery (1877–1903), which covered nearly all aspects of machine-related production, including engines, mining, railways, and iron structures. This late 19th-century source was chosen to cover the lexicon of industrialization comprehensively.
• Scoring: Every volume in the corpus was given an industrial score based on the occurrence (weighted by index frequency) of these root words, normalized by volume length.
• Robustness Checks: The study performed robustness checks using an alternative industry dictionary derived exclusively from the 1708 Dictionarium Anglo-Britannicum to ensure the results were not skewed toward words only used in the later 19th century. These checks confirmed that volumes with high industrial scores at the science-political economy nexus were the most progress-oriented.

3. Measuring Progress and Specificity

The methodology for measuring "progress-oriented sentiment" (based on dictionaries of synonyms for progress) was designed to validate the idea that the application of knowledge could improve the condition of humankind, which is central to the Industrial Enlightenment theory. Notably, words were removed from the progress dictionary if they had alternative meanings in science (like 'evolution' or 'momentum') or were not in use prior to 1643 (Isaac Newton’s birth year), specifically to avoid biasing results toward later periods of the Enlightenment and Industrial Revolution.

4. Regression Analysis

The study used regression analysis (OLS) to clarify the correlation between the language categories (science, political economy, religion) and the progress-oriented sentiment over time. Crucially, a second, more complex regression was employed to integrate the industrial score with the language categories and progress sentiment, explicitly targeting the intersection of these three dimensions to provide quantitative support for the "Industrial Enlightenment" thesis.

This methodological rigor—utilizing topic modeling (LDA), custom sentiment analysis, and industrial score dictionaries on a massive corpus of English texts—was deployed specifically to address the historical question of whether the cultural changes described by scholars like Mokyr were truly widespread enough in Britain to precede and fuel the Industrial Revolution.

The textual analysis conducted on 264,443 works printed in England between 1500 and 1900 yields three central findings regarding Enlightenment ideals, the belief in progress, and their role in the run-up to the British Industrial Revolution. These findings provide quantitative evidence supporting the hypothesis, largely associated with Joel Mokyr, that a cultural shift toward a progress-oriented view of science and industry was central to this economic transformation.

Three Main Findings from Textual Analysis

The study traced the evolution of language related to science, religion, and political economy to determine if a culture manifesting a belief in progress associated with science and industry emerged in British printed works. The three main findings are:

1. Separation and Secularization of Science

The analysis found a separation in the languages of science and religion beginning in the mid-18th century.

• By this time, there was little overlap in the language of science and religion in the corpus of volumes.
• This pattern suggests that the secularization of science became entrenched during the Enlightenment.
• Visually, the frequency of topics using both the languages of science and religion began to thin out after 1750, a trend that continued through the end of the sample period (1900).
• However, the language of religion and the language of political economy continued to share a similar, though distinct, language.

This finding aligns with the ideas espoused by Mokyr (2016), as the separation of scientific and religious language predates the main onset of the Industrial Revolution.

2. Progress-Oriented Language at the Nexus of Science and Political Economy

The analysis revealed that volumes using language at the nexus of science and political economy became measurably more progress-oriented during the Enlightenment.

• The study quantified progress-oriented sentiment using specific word dictionaries. While the language of science overall did become more progress-oriented beginning in the 18th century and persisting afterward, there was a critical caveat: works using the language of "pure" science were largely neutral with respect to progress-oriented language.
• The most progress-oriented works were those located at the intersection of the languages of science and political economy.
• Regression analysis showed that volumes containing equal parts scientific and political economy language had the highest level of progress-oriented sentiment beginning in the late 17th century, with most of this growth occurring during the 18th century.
• The timing of this increased sentiment aligns with the start of Britain's industrialization in the mid-18th century. This concentration of progress-oriented language in applied scientific works supports the idea of an "Industrial Enlightenment" where knowledge was sought to improve the condition of humankind.

3. Industrial Language and Progress Correlation

The most specific finding supporting the theory of a culture of progress associated with industrialization is that volumes using industrial language—particularly those at the science-political economy nexus—were more progress-oriented beginning in the 18th century.

• Works with higher "industrial scores" (measured by the occurrence of machine-related terminology) were more progress-oriented starting in the 18th century.
• This finding provides strong support for the "Industrial Enlightenment" hypothesis, suggesting that a belief in progress was embedded in practical, industrial volumes aimed at both scientific and non-scientific audiences with political or economic interests.
• The predicted progress sentiment was highest for volumes at the 50% science and 50% political economy nexus that also had a high industry score. Only books in the upper quartile of industry scores had progress-oriented scores higher than the average for this language nexus.
• This implies that the progress-oriented cultural values were transmitted through pragmatic, industrial works that reached the broader literate population, including the artisans and skilled craftsmen who were central to industrialization.

In essence, these key findings quantitatively document that the belief in progress, a core Enlightenment ideal, was not simply abstract philosophical talk but became functionally integrated into the lexicon of applied science and industry in Britain just prior to and during the Industrial Revolution.

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The key findings act as a quantitative validation of the cultural theory of the Industrial Revolution: The measured secularization of science and the observable rise of progress-oriented language concentrated specifically at the intersection of science and industry (applied knowledge) confirmed that the culture needed for sustained economic growth diffused widely across the British printed word during the pivotal Enlightenment era.

The sources demonstrate a strong alignment with prominent historical hypotheses concerning the cultural roots of economic growth, specifically focusing on Enlightenment ideals and the belief in progress as precursors to the British Industrial Revolution (1500–1900). The textual analysis acts as a quantitative validation of arguments advanced by leading economic historians.

Alignment with Joel Mokyr's "Industrial Enlightenment" Thesis

The research is explicitly built upon and designed to test the influential argument by Joel Mokyr (2016), who posits that a progress-oriented view of science was central to the emergence of the "Industrial Enlightenment" and Britain's eventual Industrial Revolution.

Core Hypotheses Confirmed:

The quantitative results derived from analyzing the vast corpus of texts strongly align with Mokyr’s core claims by addressing two primary gaps in prior evidence:

1. Secularization of Science and Entrenchment of Enlightenment Ideals: Mokyr's thesis relies on the idea that a scientific, progress-oriented culture gained prominence.
   • Alignment: The textual analysis confirms this by demonstrating a separation in the languages of science and religion beginning in the mid-18th century. This suggests that the secularization of science became entrenched during the Enlightenment. This separation of scientific and religious language predates the main onset of the Industrial Revolution, aligning with the chronological requirement of Mokyr's hypothesis that cultural shifts precede economic takeoff.
2. The "Industrial Enlightenment" and Applied Knowledge: Mokyr argues that the cultural shift involved applying scientific understanding to improve the condition of humankind, which relied heavily on skilled artisans and craftsmen who drove industrialization (the "Industrial Enlightenment").
   • Alignment: The findings directly support this practical application focus. The analysis concludes that the most progress-oriented works were located at the nexus of the languages of science and political economy (or economics or law).
   • Crucially, works using the language of "pure" science were largely neutral regarding progress-oriented language. This suggests that the vital cultural shift was not merely theoretical but centered on applied scientific works intended for both scientific and non-scientific audiences with economic interests.
3. Industrial Alignment and Progress: A specific implication of Mokyr's thesis is that works associated with industrialization should have been measurably more progress-oriented.
   • Alignment: The use of the "industrial score" confirmed that volumes employing industrial language—especially those at the science-political economy nexus—were more progress-oriented beginning in the 18th century. This strongly supports the "Industrial Enlightenment" hypothesis, indicating that these progress-oriented views were integrated into practical, industrial volumes that reached the broader literate audience, including the artisans essential for industrialization.

The overall conclusion is that the cultural values cited as important for Britain’s economic rise were imbued in the more pragmatic, industrial works using the language of science that spoke to a broader political and economic audience.

Alignment with McCloskey's Rhetoric of "Bourgeois Virtues"

The findings are also related to the claims of Deirdre N. McCloskey (2006, 2010, 2016), who argues that changes in rhetoric favoring "bourgeois virtues"—specifically, the way people spoke about work, profit, and industry—played a key role in northwestern Europe’s economic takeoff.

• Connection: Although the study did not directly test McCloskey's theory, the finding that the language of political economy (economics, law) became intensely progress-oriented when merged with the language of science implicitly supports this hypothesis. An implication of McCloskey's theory is that the language of political economy should have become more progress-oriented during this period. The results show that the combination of economic interest (political economy) and technical knowledge (science) was the precise carrier of progress sentiment.

Alignment with Broader Historical Context

The textual analysis provides quantitative confirmation of shifts documented in qualitative historical literature:

• Timing of Growth: The finding that progress-oriented language accelerated starting in the mid-17th century and rapidly expanded in the 18th century is consistent with recent estimates placing the onset of English economic growth around 1600. The sustained rise in progress sentiment in works of applied science aligns with the "much greater economic takeoff associated with industrialization" found by historians after 1800.
• 18th-Century Cultural Shift: The results align with the historical documentation that the 18th century marked "the era when scientific knowledge became an integral part of Western culture". The research confirms that this integration was strongly correlated with a belief in human improvement through applied knowledge.
• Manuals and Applied Knowledge: The analysis of manuals further confirmed that works conveying practical instruction, especially those using scientific language, were the most progress-oriented in the 18th century, reinforcing the idea that practical, technological knowledge drove the Enlightenment's impact on industrialization.

In summary, the sophisticated textual analysis methodologically supports the hypothesis that the cultural values of the Enlightenment, defined by a pragmatic, secular, and industrial belief in progress, were broadly diffused through the written word in Britain leading up to and during the Industrial Revolution.

The sources provide comprehensive insights into the categorization of volumes, which is a core methodological step used to analyze the link between Enlightenment ideals and the belief in progress leading up to the British Industrial Revolution (1500–1900). The categorization process focuses not on the traditional subject matter of a book, but on the language the volumes employed, allowing the study to track the intersection and evolution of specific cultural discourses over time.

Methodology of Volume Categorization

The categorization process involves using Latent Dirichlet Allocation (LDA) to extract latent topics, followed by a subjective and algorithmic process to group these topics into meaningful categories.

1. Topic Extraction and Initial Classification

The data corpus consists of 264,443 unique volumes published in England and written in English between 1500 and 1900.

• LDA Process: The LDA, an unsupervised machine learning algorithm, views each volume as a "bag of words" and identifies groups of words that frequently co-occur within the same volume. This process yielded 60 latent topics.
• Subjectivity: After the unsupervised extraction of 60 topics, the researchers used an algorithm to determine which topics most frequently co-existed, and then subjectively grouped the three most distinct sets of unique topics into three broad, manually labeled categories: science, religion, and political economy.
• Classification Basis: Crucially, the volumes are classified based on the language they used, not solely their traditional subject matter. For example, a work that might be recognized as science today could have predominantly used religious language in the 16th or 17th centuries, and this would be reflected in its categorization.

2. Deriving Categorical Weights for Volumes

To accurately reflect the mix of ideas within each work, the research generated time-varying categorical weights ($\alpha_{t,v}$) for all 60 topics, and subsequently for each individual volume.

• Placement and Scoring: For each topic and category, a yearly "score" was calculated based on how often that topic co-occurred with the three core topics chosen to represent the category.
• Convex Combination: These raw scores were normalized into a convex combination for each topic in each year, where the coefficients represented the extent to which the topic corresponded to each of the three categories.
• Volume Weights: These topic-level category coefficients ($\beta_{t,c}$) were then multiplied by the original topic weights ($\alpha_{t,v}$) for each volume to create the final categorical weights for that volume: $Science_{v}$, $PoliticalEconomy_{v}$, and $Religion_{v}$. These weights sum to one for each volume.
• Classification: A volume was then classified as predominantly using one of the three languages based on which weight was the highest.

3. Insights into the Evolution of Language Categories

The volume categorization provides key evidence of cultural change relevant to Enlightenment ideals and progress:

Secularization and Separation (Religion vs. Science)

The categorization revealed a separation in the languages of science and religion beginning in the mid-18th century.

• By the mid-18th century, there was little overlap in the language of science and religion in the corpus, indicating the secularization of science became entrenched during the Enlightenment.
• This is visibly apparent in the simplex plots, where the religion-science axis is essentially devoid of volumes starting in the mid-18th century, contrasting sharply with the volume distributions on the political economy-science and religion-political economy axes.
• This pattern supports the Enlightenment hypothesis by showing that the cultural shift (secularization) predated the main industrialization period.

The Rise of Applied Science (Science and Political Economy Nexus)

The categorized volumes demonstrated that the belief in progress was concentrated precisely where economic interests met scientific language.

• The analysis found a shared language for science and political economy throughout the period.
• The textual analysis demonstrated that the most progress-oriented volumes were those located at the nexus of the languages of science and political economy.
• Conversely, volumes using the language of "pure" science were largely neutral regarding progress-oriented language.
• This finding suggests that the cultural values central to the Industrial Enlightenment—the idea that knowledge could be used for the improvement of humankind—were embedded in practical, applied scientific works rather than purely theoretical texts. These pragmatic works were aimed at "both a scientific and non-scientific audience; those with some type of political or economic (but not religious) interest".

4. Alternative Categorizations

The researchers also performed analyses using alternative categorizations to test the robustness of the findings.

• When the "political economy" category was replaced with more specific categories—economics, law, or arts and literature—the results remained qualitatively similar.
• Specifically, when using law or economics, the predicted values at the intersection of the languages of science and law/economics rose sharply in the 18th century, mirroring the political economy results.
• However, when arts and literature was used, the language nexus with science was not as consistently progress-oriented in the 19th century as the science-political economy nexus was. This supports the hypothesis that the rise in progress sentiment was most tightly coupled with applied science (science applied to economic or legal matters).

In summary, volume categorization was instrumental in moving beyond anecdotal evidence to quantitatively demonstrate that the cultural changes—specifically the secularization of scientific language and the injection of progress-oriented sentiment into applied scientific and industrial works—occurred consistently in the period leading up to and during Britain's Industrial Revolution.

The central conclusion of the thesis, based on a textual analysis of 264,443 works printed in England between 1500 and 1900, is that the cultural values cited as important for Britain's economic rise—specifically, the Enlightenment ideals of progress and applied scientific pursuit—were broadly diffused through the printed word in the centuries leading up to and during the Industrial Revolution.

This quantitative evidence supports the "Industrial Enlightenment" hypothesis, championed by Joel Mokyr (2009, 2016), which argues that a progress-oriented view of science and industry was central to Britain's economic takeoff.

The authors summarize their thesis with three main findings that collectively lead to this conclusion:

1. Secularization of Science

There was a separation in the languages of science and religion beginning in the mid-18th century.

• By the mid-18th century, there was little overlap in the language of science and religion in the corpus of volumes.
• This pattern suggests that the secularization of science became entrenched during the Enlightenment.
• The trend of separation between scientific and religious language predates the onset of the Industrial Revolution, consistent with the hypothesis that cultural shifts enabled the economic changes.

2. Progress-Oriented Language in Applied Science

Volumes using language at the nexus of science and political economy became more progress-oriented during the Enlightenment.

• While the language of science overall did become more progress-oriented beginning in the 18th century, the analysis revealed a critical caveat: works using the language of "pure" science were largely neutral with respect to progress-oriented language.
• The highest level of progress-oriented sentiment was found in works combining scientific and political economy language, indicating that the cultural shift was centered on applied scientific works.

3. Industrial Alignment with Progress

Volumes employing industrial language—especially those at the science-political economy nexus—were more progress-oriented beginning in the 18th century.

• Works with higher industrial scores became measurably more progress-oriented starting in the 18th century.
• The results indicate that progress-oriented views were imbued in the pragmatic, industrial volumes that sought to reach both a scientific and non-scientific audience, especially those with political or economic interests.
• This specific correlation among progress, industry, and applied knowledge strongly supports the "Industrial Enlightenment" thesis.

In conclusion, the thesis argues that the data provide strong evidence that the cultural values—a pragmatic, secular, and progress-focused attitude towards applied knowledge—were successfully diffused to elite artisans and skilled craftsmen through accessible printed works in Britain, playing a central role in quickening the pace of technological innovation and enabling the massive economic changes of the 18th and 19th centuries.