As a rational being, he now places his behavior under the control of abstractions. He will no longer tolerate being carried away by sudden impressions, by intuitions.

The irrationality of a thing is no argument against its existence, rather a condition of it.

Reason is the cause of our falsification of the evidence of the senses. In so far as the senses show becoming, passing away, change, they do not lie.

There is no place in a fanatic's head where reason can enter.

The great majority of people does not consider it contemptible to believe this or that and to live accordingly, without first having given themselves an account of the final and most certain reasons pro and con, and without even troubling themselves about such reasons afterward: the most gifted men and the noblest women still belong to this great majority.

When someone hides something behind a bush and looks for it again in the same place and finds it there as well, there is not much to praise in such seeking and finding. Yet this is how matters stand regarding seeking and finding truth within the realm of reason.