provided intellectuals across Europe with a high-quality survey of human knowledge. In d'Alembert's Preliminary Discourse to the Encyclopedia of Diderot, the work's goal to record the extent of human knowledge in the arts and sciences is outlined: The massive work was arranged according to a "tree of knowledge". The tree reflected the marked division between the arts and sciences, which was largely a result of the rise of empiricism. Both areas of knowledge were united by philosophy, or the trunk of the tree of knowledge. The Enlightenment's desacrilization of religion was pronounced in the tree's design, particularly where theology accounted for a peripheral branch, with black magic as a close neighbour. As the Encyclopédie gained popularity, it was published in quarto and octavo editions after 1777. The quarto and octavo editions were much less expensive than previous editions, making the Encyclopédie more accessible to the non-elite. Robert Darnton estimates that there were approximately 25,000 copies of the Encyclopédie in circulation throughout France and Europe before the French Revolution. The extensive yet affordable encyclopedia came to represent the transmission of Enlightenment and scientific education to an expanding audience. Popularization of science One of the most important developments that the Enlightenment era brought to the discipline of science was its popularization. An increasingly literate population seeking knowledge and education in both the arts and the sciences drove the expansion of print culture and the dissemination of scientific learning. The new literate population was precipitated by a high rise in the availability of food; this enabled many people to rise out of poverty, and instead of paying more for food, they had money for education. Popularization was generally part of an overarching Enlightenment ideal that endeavoured "to make information available to the greatest number of people". As public interest in natural philosophy grew during the 18th century, public lecture courses and the publication of popular texts opened up new roads to money and fame for amateurs and scientists who remained on the periphery of universities and academies. More formal works included explanations of scientific theories for individuals lacking the educational background to comprehend the original scientific text. Newton's celebrated Philosophiae Naturalis Principia Mathematica was published in Latin and remained inaccessible to readers without education in the classics until Enlightenment writers began to translate and analyze the text in the vernacular. The first significant work that expressed scientific theory and knowledge expressly for the