To deny, to believe, and to doubt well are to a man as the race is to a horse.

When a man who accepts the Christian doctrine lives unworthily of it, it is much clearer to say he is a bad Christian than to say he is not a Christian.

I condemn equally those who choose to praise man, those who choose to condemn him and those who choose to divert themselves, and I can only approve of those who seek with groans.

When we do not know the truth of a thing, it is good that there should exist a common error which determines the mind of man, as, for example, the moon, to which is attributed the change of seasons, the progress of diseases, etc. For the chief malady of man is a restless curiosity about things which he cannot understand; and it is not so bad for him to be in error as to be curious to no purpose.

By a peculiar prerogative, not only each individual is making daily advances in the sciences, and may make advances in morality (which is the science, by way of eminence, of living well and being happy), but all mankind together is making a continual progress in proportion as the universe grows older. So that the whole human race, during the course of so many ages, may be considered as one man who never ceases to live and learn.

The sole cause of man's unhappiness is that he does not know how to stay quietly in his room.

One has followed the other in an endless circle, for it is certain that as man's insight increases so he finds both wretchedness and greatness within himself. In a word man knows he is wretched. Thus he is wretched because he is so, but he is truly great because he knows it.

Man is to himself the most wonderful object in nature; for he cannot conceive what the body is, still less what the mind is, and least of all how a body should be united to a mind. This is the consummation of his difficulties, and yet it is his very being.

For as old age is that period of life most remote from infancy, who does not see that old age in this universal man ought not to be sought in the times nearest his birth, but in those most remote from it?