To know how to suggest is the great art of teaching. To attain it we must be able to guess what will interest; we must learn to read the childish soul as we might a piece of music. Then, by simply changing the key, we keep up the attraction and vary the song.

It gives liberty and breadth to thought, to learn to judge our own epoch from the point of view of universal history, history from the point of view of geological periods, geology from the point of view of astronomy.

Self-interest is an inexhaustible source of convenient illusions. The number of beings who wish to see truly is extraordinarily small.

If man was what he ought to be, he would be adored by the animals.

To marry unequally is to suffer equally.

At bottom there is but one subject of study: the forms and metamorphoses of mind. All other subjects may be reduced to that; all other studies bring us back to this study.

Will localizes us, thought universalizes us.