A comfortable old age is the reward of a well-spent youth. Instead of its bringing sad and melancholy prospects of decay, it would give us hopes of eternal youth in a better world.
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.
As I approve of a youth that has something of the old man in him, so I am no less pleased with an old man that has something of the youth. He that follows this rule may be old in body, but can never be so in mind.
As long as any adult thinks that he, like the parents and teachers of old, can become introspective, invoking his own youth to understand the youth before him, he is lost.