Information is not knowledge. The only source of knowledge is experience. You need experience to gain wisdom.

Do not worry about your difficulties in Mathematics. I can assure you mine are still greater.

People like you and I, though mortal of course like everyone else, do not grow old no matter how long we live.

The more I learn, the more I realize I don't know.

The ideals which have lighted my way, and time after time have given me new courage to face life cheerfully, have been Kindness, Beauty, and Truth. Without the sense of kinship with men of like mind, without the occupation with the objective world, the eternally unattainable in the field of art and scientific endeavors, life would have seemed to the empty. The trite objects of human efforts — possessions, outward success, luxury—have always seemed to me contemptible.

You never fail until you stop trying.

Strenuous intellectual work and the study of God's Nature are the angels that will lead me through all the troubles of this life with consolation, strength, and uncompromising rigor.