It's a work in progress, with articles being added as they are translated, but this is a fantastic site. The Encyclopedia is the crowning achievement of the Enlightenment. It was designed to be a repository of human knowledge, but it was also a subversive polemic articulating the best humanist thought of the age with some of the greatest Enlightenment philosophers (Voltaire, Montesquieu, Rosseau, etc.) contributing articles.
Here's a sample from the entry "prejudice"
Prejudice, a false judgment made by the mind about the nature of things after an insufficient exercise of the intellectual faculties, this unhappy fruit of ignorance thwarts the understanding, blinds and imprisons it.
Prejudices , says Bacon, the man who has meditated the most on this subject, are just so many spectres and phantoms sent to earth by an evil genius in order to torment men; but they are a kind of infectious illness which, like all epidemic diseases, primarily attacks the people, women, children, and old men, and which yields to nothing but maturity and reason.
Prejudice is not always a matter of judgment's being taken by surprise when shrouded in darkness or seduced by false gleams of light; it also emanates from the unfortunate inclination of the mind to go astray, which plunges it into error despite any resistance; for the human mind, far from resembling that faithful crystal whose surface receives rays and transmits them without alteration, is much more like a kind of magic mirror, which distorts objects, and reflects only shadows or monsters.