Beyond a doubt truth bears the same relation to falsehood as light to darkness.

When you put your hand in a flowing stream, you touch the last that has gone before and the first of what is still to come.

The Medici created and destroyed me.

The desire to know is natural to good men.

For those colours which you wish to be beautiful, always first prepare a pure white ground.

Every action done by nature is done in the shortest way.

To speak of this subject you must... explain the nature of the resistance of the air, in the second the anatomy of the bird and its wings, in the third the method of working the wings in their various movements, in the fourth the power of the wings and the tail when the wings are not being moved and when the wind is favourable to serve as guide in various movements.