Learning how to live and how to die.

From Leonardo:

Simplicity is the ultimate sophistication.

There are three classes of people: those who see. Those who see when they are shown. Those who do not see.

Where the spirit does not work with the hand there is no art.

I have been impressed with the urgency of doing. Knowing is not enough; we must apply. Being willing is not enough; we must do.

Time stays long enough for anyone who will use it.

Iron rusts from disuse; water loses its purity from stagnation ... even so does inaction sap the vigour of the mind.

There shall be wings! If the accomplishment be not for me, 'tis for some other.

The depth and strength of a human character are defined by its moral reserves. People reveal themselves completely only when they are thrown out of the customary conditions of their life, for only then do they have to fall back on their reserves.

Where there is shouting, there is no true knowledge.

Learning never exhausts the mind.

Our life is made by the death of others.

The function of muscle is to pull and not to push, except in the case of the genitals and the tongue.

He who loves practice without theory is like the sailor who boards ship without a rudder and compass and never knows where he may cast.

People react to fear, not love - they don't teach that in Sunday School, but it's true.

As a well spent day brings happy sleep, so a life well spent brings happy death.

BONUS:

Watch your thoughts, for they become words.
Watch your words, for they become actions.
Watch your actions, for they become habits.
Watch your habits, for they become character.
Watch your character, for it becomes your destiny.