Leonardo Da Vinci: Use

“I have from an early age abjured the use of meat, and the time will come when men such as I will look upon the murder of animals as they now look upon the murder of men.”

Leonardo Da Vinci

Quoted allegedly "From da Vinci`s Notes" in Jon Wynne-Tyson: The Extended Circle. A Dictionary of Humane Thought. Centaur Press 1985, p. 65 books.google http://books.google.de/books?id=1mMbAQAAIAAJ&q=murder.
Actually the quote is not authentic but made up from a novel by Dmitri Merejkowski (w:Dmitry Merezhkovsky) entitled "The Romance of Leonardo da Vinci" (La Résurrecton de Dieux 1901), translated from Russian into English by Herbert Trench. G.P. Putnam's Sons New York and London, The Knickerbocker Press. There, in Book (i.e. chapter) VI, entitled The Diary of Giovanni Boltraffio, one finds the following:
The master [Leonardo da Vinci] permits harm to no living creatures, not even to plants. Zoroastro http://it.wikipedia.org/wiki/Tommaso_Masini tells me that from an early age he has abjured meat, and says that the time shall come when all men such as he will be content with a vegetable diet, and will think on the murder of animals as now they think on the murder of men ( p. 226 books.google http://books.google.de/books?id=g_pa0OaYX64C&pg=PA226).
However, despite the quote's false attribution, da Vinci was in fact a vegetarian.
Misattributed

Men , Age , Time , Animals

“Just as iron rusts unless it is used, and water putrifies or, in cold, turns to ice, so our intellect spoils unless it is kept in use.”

Leonardo Da Vinci

The Notebooks of Leonardo da Vinci (1883), XIX Philosophical Maxims. Morals. Polemics and Speculations.
Variant: Just as iron rusts from disuse... even so does inaction spoil the intellect.

Water

“Time stays long enough for those who use it.”

Leonardo Da Vinci

Time

“Thou, O God, dost sell us all good things at the price of labour.”

Leonardo Da Vinci

The Notebooks of Leonardo da Vinci (1883), XIX Philosophical Maxims. Morals. Polemics and Speculations.

God

“Blinding ignorance does mislead us. O! Wretched mortals, open your eyes!”

Leonardo Da Vinci

The Notebooks of Leonardo da Vinci (1883), XIX Philosophical Maxims. Morals. Polemics and Speculations.
Context: Blind ignorance misleads us thus and delights with the results of lascivious joys. Because it does not know the true light. Because it does not know what is the true light. Vain splendour takes from us the power of being.... behold! for its vain splendour we go into the fire, thus blind ignorance does mislead us. That is, blind ignorance so misleads us that... O! wretched mortals, open your eyes.

“The acquisition of any knowledge is always of use to the intellect, because it may thus drive out useless things and retain the good. For nothing can be loved or hated unless it is first known.”

Leonardo Da Vinci

The Notebooks of Leonardo da Vinci (1883), XIX Philosophical Maxims. Morals. Polemics and Speculations.

Love , Hate , Knowledge

“Anyone who conducts an argument by appealing to authority is not using his intelligence; he is just using his memory.”

Leonardo Da Vinci

Intelligence , Memory

“Man has much power of discourse which for the most part is vain and false; animals have but little, but it is useful and true, and a small truth is better than a great lie.”

Leonardo Da Vinci

The Notebooks of Leonardo da Vinci (1883), XIX Philosophical Maxims. Morals. Polemics and Speculations.
Source: Leonardo's Notebooks

Truth , Lie , Animals , Parting

“These rules are of use only in correcting the figures; since every man makes some mistakes in his first compositions and he who knows them not, cannot amend them. But you, knowing your errors, will correct your works and where you find mistakes amend them, and remember never to fall into them again. But if you try to apply these rules in composition you will never make an end, and will produce confusion in your works.”

Leonardo Da Vinci

The Notebooks of Leonardo da Vinci (1883), I Prolegomena and General Introduction to the Book on Painting

Error

“Seeing that I can find no subject specially useful or pleasing — since the men who have come before me have taken for their own every useful or necessary theme — I must do like one who, being poor, comes last to the fair, and can find no other way of providing himself than by taking all the things already seen by other buyers, and not taken but refused by reason of their lesser value. I, then, will load my humble pack with this despised and rejected merchandise, the refuse of so many buyers; and will go about to distribute it, not indeed in great cities, but in the poorer towns, taking such a price as the wares I offer may be worth.”

Leonardo Da Vinci

The Notebooks of Leonardo da Vinci (1883), I Prolegomena and General Introduction to the Book on Painting

Men , Way

“Beyond a doubt truth bears the same relation to falsehood as light to darkness; and this truth is in itself so excellent that, even when it dwells on humble and lowly matters, it is still infinitely above uncertainty and lies, disguised in high and lofty discourses; because in our minds, even if lying should be their fifth element, this does not prevent that the truth of things is the chief nutriment of superior intellects, though not of wandering wits. But you who live in dreams are better pleased by the sophistical reasons and frauds of wits in great and uncertain things, than by those reasons which are certain and natural and not so far above us.”

Leonardo Da Vinci

The Notebooks of Leonardo da Vinci (1883), XIX Philosophical Maxims. Morals. Polemics and Speculations.

Truth , Dreams , Lying , Fraud

“Whoever in discussion adduces authority uses not intellect but rather memory.”

Leonardo Da Vinci

Variant translations:
Anyone who conducts an argument by appealing to authority is not using his intelligence; he is just using his memory.
As quoted in The Book of Unusual Quotations (1957) by Rudolf Flesch, p. 12
Any one who in discussion relies upon authority uses, not his understanding, but rather his memory.
The Notebooks of Leonardo da Vinci (1883), I Prolegomena and General Introduction to the Book on Painting

Memory

“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.”

Leonardo Da Vinci

The Notebooks of Leonardo da Vinci (1883), VII On the Proportions and on the Movements of the Human Figure

Beauty , Appearance , Sun , Perfection

“I myself have proved it to be of no small use, when in bed in the dark, to recall in fancy the external details of forms previously studied, or other noteworthy things conceived by subtle speculation; and this is certainly an admirable exercise, and useful for impressing things on the memory.”

Leonardo Da Vinci

The Notebooks of Leonardo da Vinci (1883), IX The Practice of Painting

Exercises , Study , Memory

“Movement will fail sooner than usefulness.”

Leonardo Da Vinci

The Notebooks of Leonardo da Vinci (1883), X Studies and Sketches for Pictures and Decorations

“The city will gain beauty worthy of its name and to you it will be useful by its revenues, and the eternal fame of its aggrandizement.”

Leonardo Da Vinci

These notes were possibly written in preparation for a letter. The meaning is obscure.
The Notebooks of Leonardo da Vinci (1883), XIX Philosophical Maxims. Morals. Polemics and Speculations.

Beauty

“And if you should say that the shells were carried by the waves, being empty and dead, I say that where the dead went they were not far removed from the living; for in these mountains living ones are found, which are recognisable by the shells being in pairs; and they are in a layer where there are no dead ones; and a little higher up they are found, where they were thrown by the waves, all the dead ones with their shells separated, near to where the rivers fell into the sea, to a great depth; like the Arno which fell from the Gonfolina near to Monte Lupo, where it left a deposit of gravel which may still be seen, and which has agglomerated; and of stones of various districts, natures, and colours and hardness, making one single conglomerate. And a little beyond the sandstone conglomerate a tufa has been formed, where it turned towards Castel Florentino; farther on, the mud was deposited in which the shells lived, and which rose in layers according to the levels at which the turbid Arno flowed into that sea. And from time to time the bottom of the sea was raised, depositing these shells in layers, as may be seen in the cutting at Colle Gonzoli, laid open by the Arno which is wearing away the base of it; in which cutting the said layers of shells are very plainly to be seen in clay of a bluish colour, and various marine objects are found there. And if the earth of our hemisphere is indeed raised by so much higher than it used to be, it must have become by so much lighter by the waters which it lost through the rift between Gibraltar and Ceuta; and all the more the higher it rose, because the weight of the waters which were thus lost would be added to the earth in the other hemisphere. And if the shells had been carried by the muddy deluge they would have been mixed up, and separated from each other amidst the mud, and not in regular steps and layers — as we see them now in our time.”

Leonardo Da Vinci

The Notebooks of Leonardo da Vinci (1883), XVI Physical Geography

Mountain , Nature , Water , Time

“A bird makes the same use of wings and tail in the air as a swimmer does of his arms and legs in the water.”

Leonardo Da Vinci

The Notebooks of Leonardo Da Vinci (1938), XVII Flight

Bird , Water

“That is not riches, which may be lost; virtue is our true good and the true reward of its possessor. That cannot be lost; that never deserts us, but when life leaves us. As to property and external riches, hold them with trembling; they often leave their possessor in contempt, and mocked at for having lost them.”

Leonardo Da Vinci

The Notebooks of Leonardo da Vinci (1883), XIX Philosophical Maxims. Morals. Polemics and Speculations.