A fool is someone whose pencil wears out before its eraser does.
Being defeated is often a temporary condition. Giving up is what makes it permanent.
If your head tells you one thing and your heart tells you another, before you do anything, you should first decide whether you have a better head or a better heart.
The essence of America is finding and maintaining that perfect, delicate balance between freedom ‘to’ and freedom ‘from.’
The length of your education is less important than its breadth, and the length of your life is less important than its depth.
Think of a hypothesis as a card. A theory is a house made of hypotheses.
To acquire knowledge, one must study; but to acquire wisdom, one must observe.