Physical concepts are free creations of the human mind, and are not, however it may seem, uniquely determined by the external world.

That is the way to learn the most, that when you are doing something with such enjoyment that you don't notice that the time passes.

Without "ethical culture", there is no salvation for humanity.

Strange is our situation here on Earth. Each of us comes for a short visit, not knowing why, yet sometimes seeming to divine a purpose. From the standpoint of daily life, however, there is one thing we do know: that man is here for the sake of other men - above all for those upon whose smiles and well-being our own happiness depends.

There are two ways to live: you can live as if nothing is a miracle; you can live as if everything is a miracle.

Academic chairs are many, but wise and noble teachers are few; lecture-rooms are numerous and large, but the number of young people who genuinely thirst after truth and justice is small

It is a very grave mistake to think that the enjoyment of seeing and searching can be promoted by means of coercion and a sense of duty.