Baruch Spinoza

If the way which I have pointed out as leading to this result (i.e., power over the emotions by which the wise man surpasses the ignorant man) seems exceedingly hard, it may nevertheless be discovered. Needs must it be hard, since it is so seldom found. How would it be possible, if salvation were ready to our hand, and could without great labour be found, that it should be by almost all men neglected? But all things excellent are as difficult as they are rare.

I should attempt to treat human vice and folly geometrically… the passions of hatred, anger, envy, and so on, considered in themselves, follow from the necessity and efficacy of nature… I shall, therefore, treat the nature and strength of the emotion in exactly the same manner, as though I were concerned with lines, planes, and solids.

As men’s habits of mind differ, so that some more readily embrace one form of faith, some another, for what moves one to pray may move another to scoff, I conclude … that everyone should be free to choose for himself the foundations of his creed, and that faith should be judged only by its fruits.

Many errors, of a truth, consist merely in the application of the wrong names of things. For if a man says that the lines which are drawn from the centre of the circle to the circumference are not equal, he understands by the circle, at all events for the time, something else than mathematicians understand by it.