I thought I was learning to live; I was only learning to die. - Leonardo da Vinci

Necessity is the mistress and guardian of Nature.

Painting is concerned with all the ten attributes of sight, namely darkness and brightness, substance and colour, form and place, remoteness and nearness, movement and rest; and it is with these attributes that this my small book will be woven, recalling to the painter by what rules and in what way he ought by his art to imitate all things that are the work of nature and the adornment of the world.

Those who fall in love with practice without science are like a sailor who enters a ship without a helm or a compass, and who never can be certain whither he is going.