In rivers, the water that you touch is the last of what has passed and the first of that which comes; so with present time. - Leonardo da Vinci

Men of lofty genius sometimes accomplish the most when they work least, for their minds are occupied with their ideas and the perfection of their conceptions, to which they afterwards give form.

Experience shows us that the air must have darkness beyond it and yet it appears blue. If you produce a small quantity of smoke from dry wood and the rays of the sun fall on this smoke, and if you then place behind the smoke a piece of black velvet on which the sun does not shine, you will see that all the smoke which is between the eye and the black stuff will appear of a beautiful blue colour. And if instead of the velvet you place a white cloth smoke, that is too thick smoke, hinders, and too thin smoke does not produce, the perfection of this blue colour. Hence a moderate amount of smoke produces the finest blue.

The vine that has grown old on an old tree falls with the ruin of that tree, and through that bad companionship must perish with it.