Quotes from the Notebooks of Leonardo da Vinci:These quotes are primarily from the English translation by Jean Paul Richter of 1888 (not all of them can be confirmed).
My works are the issue of pure and simple experience, who is the one true mistress.
Here forms, here colours, here the character of every part of the universe are concentrated to a point; and that point is so marvellous a thing ... Oh! marvellous, O stupendous Necessity— by thy laws thou dost compel every effect to be the direct result of its cause, by the shortest path. These are miracles...
The eye — which sees all objects reversed — retains the images for some time.
Let no man who is not a Mathematician read the elements of my work.
As a well-spent day brings happy sleep, so life well used brings happy death.
Life well spent is long.
Poor is the pupil that does not surpass his master.
Shun those studies in which the work that results dies with the worker.
Whoever in discussion adduces authority uses not intellect but rather memory.
Variant: Any one who in discussion relies upon authority uses, not his understanding, but rather his memory.
Iron rusts from disuse; stagnant water loses its purity and in cold weather becomes frozen; even so does inaction sap the vigor of the mind.
It is easier to resist at the beginning than at the end.
Necessity is the mistress and guardian of Nature.
Human subtlety...will never devise an invention more beautiful, more simple or more direct than does nature, because in her inventions nothing is lacking, and nothing is superfluous.
Mechanics is the paradise of the mathematical sciences because by means of it one comes to the fruits of mathematics.
I am not to blame for putting forward, in the course of my work on science, any general rule derived from a previous conclusion.
The Book of the science of Mechanics must precede the Book of useful inventions.
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.
I know that many will call this useless work.