We need not regard what good a friend has done us, but only his desire to do us good.

There is no one who cannot derive great help and great benefit from learning; but there are also only a few people who do not receive a great harm from the light and knowledge they have received by learning, unless they use their knowledge in a manner both fit and natural for them.

Social intercourse, even friendship among most people, is a merely a business arrangement that lasts only so long as there is need.

We learn as much by others' failings as by their teachings. Examples of imperfection is just as useful for achieving perfection as are models of competence and perfection.

There is always enough self-love hidden beneath the greatest devoutness to set limits on charity.

In knowledge of human affairs, we should never allow our minds to be enslaved by others by subjecting ourselves to their whims. We must maintain freedom of thought, and never accept anything of purely human authority into our heads. When we are presented with a diversity of opinions, we must choose, if we can; if we cannot, we must remain in doubt.

There are many people who are so inclined to say "no" that the "no" always precedes whatever we say to them. This negative quality makes them so disagreeable that, even if they do what we want them to or agree with what we say, they always lose the pleasure that they might have received had they not started off so badly.