Life would be infinitely happier if we could only be born at the age of eighty and gradually approach eighteen.

Common sense is the collection of prejudices acquired by age eighteen.

The great secret that all old people share is that you really haven't changed in seventy or eighty years. Your body changes but you don't change at all. And that of course causes great confusion.

Anyone who stops learning is old whether at twenty or eighty. Anyone who keeps learning stays young. The greatest thing in life is to keep your mind young.