A child who passes through many hands in turn, can never be well brought up. At every change he makes a secret comparison, which continually tends to lessen his respect for those who control him, and with it their authority over him. If once he thinks there are grown-up people with no more sense than children the authority of age is destroyed and his education is ruined.

That man is truly free who desires what he is able to perform, and does what he desires.

To live is not to breathe but to act. It is to make use of our organs, our senses, our faculties, of all the parts of ourselves which give us the sentiment of our existence. The man who has lived the most is not he who has counted the most years but he who has most felt life.

Interest is the spur of the people, but glory that of great souls.

To be sane in a world of madman is in itself madness.

The person who has lived the most is not the one with the most years but the one with the richest experiences.

Chemistry... is like the maid occupied with daily civilisation; she is busy with fertilisers, medicines, glass, insecticides ... for she dispenses the recipes.