If reason be a gift of Heaven, and we can say as much of faith, Heaven has certainly made us two gifts not only incompatible, but in direct contradiction to each other. In order to solve the difficulty, we are compelled to say either that faith is a chimera or that reason is useless.
Denis DiderotGentleness and peacefulness regulate our proceedings; theirs are dictated by fury. We employ reason, they accumulate faggots. They preach nothing but love, and breathe nothing but blood. Their words are humane, but their hearts are cruel.
Denis DiderotAs long as the centuries continue to unfold, the number of books will grow continually, and one can predict that a time will come when it will be almost as difficult to learn anything from books as from the direct study of the whole universe. It will be almost as convenient to search for some bit of truth concealed in nature as it will be to find it hidden away in an immense multitude of bound volumes.
Denis DiderotA thing is not proved because no one has ever questioned it... Skepticism is the first step toward truth.
Denis DiderotAll things must be examined, debated, investigated without exception and without regard for anyone's feelings... We must run roughshod over all these ancient puerilities, overturn the barriers that reason never erected, give back to the arts and sciences the liberty that is so precious to them.
Denis Diderot