No human investigation can claim to be scientific if it doesn't pass the test of mathematical proof.
Leonardo da VinciTest knowledge through experience, be prepared to make mistakes, and be persistent about it.
Leonardo da VinciI have been impressed with the urgency of doing. Knowing is not enough; we must apply. Being willing is not enough; we must do.
Leonardo da VinciA painter should begin every canvas with a wash of black, because all things in nature are dark except where exposed by the light.
Leonardo da VinciJust as a well-filled day brings blessed sleep, so a well-employed life brings a blessed death.
Leonardo da VinciThe Bactrian have two humps; the Arabian one only. They are swift in battle and most useful to carry burdens. This animal is extremely observant of rule and measure, for it will not move if it has a greater weight than it is used to, and if it is taken too far it does the same, and suddenly stops and so the merchants are obliged to lodge there.
Leonardo da VinciJust as eating against one's will is injurious to health, so studying without a liking for it spoils the memory, and it retains nothing it takes in.
Leonardo da VinciThere is no higher or lower knowledge, but one only, flowing out of experimentation.
Leonardo da VinciWho would believe that so small a space could contain the images of all the universe?
Leonardo da VinciO speculators about perpetual motion, how many vain chimeras have you created in the like quest? Go and take your place with the seekers after gold.
Leonardo da VinciStudy me, reader, if you delight in me, because on very few occasions shall I return to the world, and because the patience for this profession is found in very few, and only in those who wish to compose things anew. Come, oh men, to see the miracles that such studies will disclose to nature.
Leonardo da VinciIt's not enough that you believe what you see. You must also understand what you see.
Leonardo da VinciAny color is more distinctly seen when opposed to its contrary: thus, black on white, blear near yellow, green near red, and so on.
Leonardo da VinciIt is ordained that to the ambitious, who derive no satisfaction from the gifts of life and the beauty of the world, life shall be a cause of suffering, and they shall possess neither the profit nor the beauty of the world.
Leonardo da VinciThose 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.
Leonardo da VinciWhen Fortune comes, seize her in front with a sure hand, because behind she is bald.
Leonardo da VinciPainting is poetry that is seen rather than felt, and poetry is painting that is felt rather than seen.
Leonardo da VinciEvery now and then go away, have a little relaxation, for when you come back to your work your judgment will be surer. Go some distance away because then the work appears smaller and more of it can be taken in at a glance and a lack of harmony and proportion is more readily seen.
Leonardo da VinciPainting 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.
Leonardo da VinciExperience never misleads; what you are misled by is only your judgment, and this misleads you by anticipating results from experience of a kind that is not produced by your experiments.
Leonardo da VinciGiven the cause nature produces the effect in the briefest manner that it can employ.
Leonardo da VinciOld age takes in part savoury wisdom for its food - see to that your old age will not lack in nourishment.
Leonardo da VinciPeople reveal themselves completely only when they are thrown out of the customary conditions of their life.
Leonardo da VinciO neglectful Nature, wherefore art thou thus partial, becoming to some of thy children a tender and benignant mother, to others a most cruel and ruthless stepmother? I see thy children given into slavery to others without ever receiving any benefit, and in lieu of any reward for the services they have done for them they are repaid by the severest punishments.
Leonardo da VinciThe painter who draws merely by practice and by eye, without any reason, is like a mirror which copies every thing placed in front of it without being conscious of their existence.
Leonardo da VinciShadow is the diminution alike of light and of darkness, and stands between darkness and light.
Leonardo da VinciIt should not be hard for you to stop sometimes and look into the stains of walls, or ashes of a fire, or clouds, or mud or like places, in which...you may find really marvellous ideas.
Leonardo da Vinci