Leonardo Da Vinci was a keen observer and student of nature. His notes on The Nature of Water, from The notebooks of Leonardo da Vinci , Translation by Edward MacCurdy (1955) are perceptive and eloquent:
“Water is that which serves the vital humour of this arid earth.
…Thus hither and thither, up and down, it ranges, never resting at all in quietude, always flowing to help wherever the vital humours fails.
Now taking away the soil, now adding to it, here depositing logs there stones here bearing sand there mud, with nothing stable in bed or bank:
Now rushing on with headlong course, now descending in tranquility, now showing itself with fierce aspect, now appearing bright and calm, now mingling with the air in fine spray, now falling down in tempestuous rain; now changed to snow or storms of hail, now bathing the air with fine rain; so also now turning to ice and now hot; never keeping any stability; now rising aloft in thin cloud…” [p.736]
“…Thus within and without it [water] goes, ever changing, now rising with fortuitous movement and now descending in natural liberty.
So united together it goes ranging about in continual revolution.
Rushing now here now there, up and down, never resting at all in quiet either in its course of in its own nature, it has nothing of its own but seizes hold on everything, assuming as many different natures as the places are different through which it passes, acting just as the mirror does when it assumes within itself as many images as are the objects which pass before it. So it is in a state of continual change, sometimes of position and sometimes of colour, now enclosing in itself new scents and savours, now keeping new essences or qualities, showing itself now deadly now lifegiving, at on time dispersing itself through the air, at another suffering itself to be sucked up by the heat, and now arriving at the region of cold where the heat that was its guide is restricted by it.” [p. 646]
… It [water] is the increase and humour of all vital bodies. Without it nothing retains its first form. It unites and augments bodies by its increase.
Nothing lighter than itself can penetrate it without violence.
It readily raises itself by heat in thin vapour through the air. Cold causes it to freeze. Stagnation make it foul. That is, heat sets it in movement, cold causes it to freeze, immobility corrupts it.
It assumes every odour, colour and flavour, and of itself it has nothing. It percolates through all porous bodies. Against its fury no human defence avails, or if it should avail it is not for long. In its rapid course it often serves as a support to things heavier than itself. It can lift itself up by movement or bound as far as it sinks down. [p. 666]
“Water, which is the vital humour of the terrestrial machine, moves by its own natural heat.” [p. 710]
“Without it [water] nothing can exist among us.” [p. 734]