As you cannot do what you want, Want what you can do

He who does not understand the supreme certainty of mathematics is wallowing in confusion.

A day will come in which men will look upon an animal's murder the same way they look today upon a man's murder.

Just as a well-filled day brings blessed sleep, so a well-employed life brings a blessed death.

For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and there you will long to return.

The senses are of the earth, the reason stands apart from them in contemplation.

O Lord, thou givest us everything, at the price of an effort.