It is not enough to have a good mind; the main thing is to use it well. And yet there are persons who flatter themselves that they think very clearly, who in reality only think with the prejudices of their age.

The peculiarity of the evidence of mathematics is that all the argument is on one side. There are no objections, and no answers to objections. But on every subject on which difference of opinion is possible, the truth depends on a balance of two sets of reasons.

The universe is not required to be in perfect harmony with human ambition. And yet, the most dangerous of all falsehoods is a slightly distorted truth, for a straight-out lie can be detected and opposed, but a half-truth insinuates itself into the understanding and breeds there.

The human understanding is no dry light, but receives an infusion from the will and affections; whence proceed sciences which may be called 'sciences as one would.' For what a man had rather were true he more readily believes.

The mind does not work by starting from universal principles and deducing particular consequences; it works the other way, by gathering up particular cases until the accumulated weight of them forces upon us recognition of a universal principle.