Science will stagnate if it is made to serve practical goals.

Only one who devotes himself to a cause with his whole strength and soul can be a true master. For this reason mastery demands all of a person.

My interest in science was always essentially limited to the study of principles.... That I have published so little is due to this same circumstance, as the great need to grasp principles has caused me to spend most of my time on fruitless pursuits.

Life is sacred, that is to say, it is the supreme value, to which all other values are subordinate.

How do I work? I grope.

My pacifism is not based on any intellectual theory but on a deep antipathy to every form of cruelty and hatred.

In conclusion I wish to say that in working at the problem here dealt with I have had the loyal assistance of my friend and colleague M. Besso, and that I am indebted to him for several valuable suggestions.