One does not ask of one who suffers: What is your country and what is your religion? One merely says: You suffer, that is enough for me.

The greatest derangement of the mind is to believe in something because one wishes it to be so.

When I approach a child, he inspires in me two sentiments; tenderness for what he is, and respect for what he may become.

Every chemical substance, whether natural or artificial, falls into one of two major categories, according to the spatial characteristic of its form. The distinction is between those substances that have a plane of symmetry and those that do not. The former belong to the mineral, the latter to the living world.

It would seem to me that I was committing a theft if I were to let one day go by without doing some work.

Intuition is given only to him who has undergone long preparation to receive it.

Do not put forward anything that you cannot prove by experimentation.