Leonardo da Vinci said:

"Painting is concerned with the ten things you can see; these are: darkness and brightness, substance and color, form and place, remoteness and nearness, movement and rest."

"I shall not refrain from including among these precepts a new device for the imagination which, although it may seem rather trivial and almost ludicrous, is nevertheless extremely useful in arousing the mind to various inventions. And this is, if you look at any walls spotted with stains, or with stones of various patterns, if you have to invent some setting, you may be able to see therein a resemblance to various landscapes, graced with mountains, rivers, rocks, trees, plains, great valleys and hills in varied arrangement; or, again, you may see various battles and figures in action; or strange faces and costumes, and an endless variety of things which you can distill into well drawn forms. And what happens with regard to such walls and variegated stones is just as with the sound of bells, in whose jangle you may find any name or word you choose to imagine."

"My arguments are derived solely from experiment, which is the source of all evidence, the one and only mother of true science....It is useless to conduct an argument by mere quotation from authorities; that does not prove cleverness; it only suggests a good memory."

"To draw is to learn how to see!"

"God, you sell us everything for the price of effort"

"As a well-spent day brings happy sleep, so life well used brings happy death."

"Every now and then go away, have a little relaxation. For when you come back to your work, your judgment will be surer, since to remain constantly at work will cause you to lose power of judgment"

"For once you have tasted flight, you will walk this earth with your eyes turned skyward, for there you have been, and there you long to return"

"I have offended God and mankind because my work didn't reach the quality it should have"

"Intellectual passion drives out sensuality."

"Men of genius often do the most work when it seems they are not working at all."

"Nothing can be loved or hated unless it is first understood"

"Obstacles cannot crush me; every obstacle yields to firm resolve."

"The eye is the window of the soul"

"Truth is so excellent that if it but praises small things, they become noble."

"You can never have a greater or a less dominion than that over yourself."

"In life, beauty perishes, but not in art."

"Iron rusts from disuse. Water loses its purity from stagnation .. even so does inaction sap the vigors of the mind."

"Only love makes me remember, it alone stirs my heart"