The search for truth and the desire for beauty were the twin ideals he strove to attain. The keenness of this pursuit saved him from the blemish of e… - Leonardo da Vinci

It's not enough that you believe what you see. You must also understand what you see.

Look at walls splashed with a number of stains, or stones of various mixed colours. If you have to invent some scene, you can see there resemblances to a number of landscapes, adorned with mountains, rivers, rocks, trees, great plains, valleys and hills, in various ways. Also you can see various battles, and lively postures of strange figures, expressions on faces, costumes and an infinite number of things, which you can reduce to good integrated form. This happens on such walls and varicoloured stones, (which act) like the sound of bells, in whose peeling you can find every name and word that you can imagine.
Do not despise my opinion, when I remind you that it should not hard for you to stop sometimes and look into the stains of walls, or the ashes of a fire, or clouds, or mud or like places, in which, if you consider them well, you may find really marvelous ideas. The mind of the painter is
stimulated to new discoveries, the composition of battles of animals and men, various compositions of landscapes and monstrous things, such as devils and similar things, which may bring you honor, because by indistinct things the mind is stimulated to new inventions.

Creatures shall be seen on the earth who will always be fighting one another, with the greatest losses and frequent deaths on either side. There will be no bounds to their malice; by their strong limbs the vast forests of the world shall be laid low; and when they are filled with food they shall gratify their desires by dealing out death, affliction, labour, terror, and banishment to every living thing; and then from their boundless pride they will desire to rise towards heaven, but the excessive weight of their limbs will hold them down. Nothing shall remain on the earth or under the earth or in the waters that shall not be pursued, disturbed, or spoiled, and that which is in one country removed into another. And their bodies shall be made the tomb and the means of transit of all the living bodies they have slain.
O earth, why do you not open and hurl them into the deep fissures of thy vast abysses and caverns, and no longer display in the sight of heaven so cruel and horrible a monster?