It is not the germs we need worry about. It is our inner terrain.

Herrmann Pidoux and Armand Trousseau stated 'Disease exists within us, because of us, and through us', Pasteur did not entirely disagree, 'This is true for certain diseases', he wrote cautiously, only to add immediately: 'I do not think that it is true for all of them'.

There are no such things as applied sciences, only applications of science.

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.

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

If it is a terrifying thought that life is at the mercy of the multiplication of these minute bodies [microbes], it is a consoling hope that Science will not always remain powerless before such enemies.

If science has no country, the scientist should have one, and ascribe to it the influence which his works may have in this world.