The greatest deception men suffer is from their own opinions.

All sciences are vain and full of errors that are not born of Experience, the mother of all Knowledge.

He who can copy can do.

I have wasted my hours.

I thought I was learning to live; I was only learning to die.

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.

The painter will produce pictures of little merit if he takes the works of others as his standard.