The belief that youth is the happiest time of life is founded upon a fallacy. The happiest person is the person who thinks the most interesting thoughts, and we grow happier as we grow older.

I cannot teach anybody anything. I can only make them think.

All human actions have one or more of these seven causes: chance, nature, compulsion, habit, reason, passion, desire.

They can conquer who believe they can.

No person is your friend who demands your silence, or denies your right to grow.

No man's knowledge here can go beyond his experience.

In the particular is contained the universal.