Leonardo da Vinci

Anyone who conducts an argument by appealing to authority is not using his intelligence; he is just using his memory.

While I thought that I was learning how to live, I have been learning how to die.

Learning never exhausts the mind.

It seems that it had been destined before that I should occupy myself so thoroughly with the vulture, for it comes to my mind as a very early memory, when I was still in the cradle, a vulture came down to me, he opened my mouth with his tail and struck me a few times with his tail against my lips.

Just as food eaten without appetite is a tedious nourishment, so does study without zeal damage the memory by not assimilating what it absorbs.

Each man is always in the middle of the surface of the earth and under the zenith of his own hemisphere, and over the centre of the earth.

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

The divisions of Perspective are 3, as used in drawing; of these, the first includes the diminution in size of opaque objects; the second treats of the diminution and loss of outline in such opaque objects; the third, of the diminution and loss of colour at long distances.

Weight, force and casual impulse, together with resistance, are the four external powers in which all the visible actions of mortals have their being and their end.

The Medici created and destroyed me.

The truth of things is the chief nutriment of superior intellects.

I have wasted my hours.