A brief summary of the science and inventions of Leonardo da Vinci

Leonardo da Vinci and Verrocchio. Annunciation. Uffizi Gallery.

As I pointed out in an earlier post, I’m not particularly interested in my YouTube channel at the moment. I think that, for now, I will leave YouTube to the horde of reactionaries and conspiracy theorists that has dominated YouTube and other popular websites for many years already, so that they can continue to yell into the void, accomplish nothing, and repeat establishment propaganda. I’m not greedy. I guess that I’m a bit glad that my YouTube channel hasn’t been taken down. All of my channels on other video-sharing websites got taken down some years ago because of censorship or copyright claims. I didn't get to use them for anything or to have any fun with them for long. Even my PayPal account got deleted about a decade or more ago because of censorship, since I linked it to my YouTube channel, though it didn’t bring me any income and I almost never used it. In order to confirm my suspicions, I later called PayPal and spoke to a representative. But, when I asked him why my account got deleted, he said that something strange happened. So, he couldn't activate my account again even though he tried. At least I still have my blog, though I haven’t taken it all that seriously either since I’ve tried to check if I can lose followers for some years. Well, it seems that no matter how many bad jokes I make, crazed propagandists like Alex Jones will never stop looking at my blog. What's also worth mentioning is that although Jones has been gone from YouTube for almost a decade, others have taken his place. The young, angry, badly-educated reactionary crowd that listened to Jones and voted for Donald Trump in 2016 is still there. Some people have figured out that they can gain many subscribers and make money by pandering to this huge right-wing crowd and telling them what they want to hear. So, nowadays, I usually see videos of reactionaries insulting, attacking, and trying to silence people that they don't agree with in the feed of my app even though I don't watch these videos. And Jones himself hasn't gone anywhere. Since he knows what to say and do in order to continue to get support from certain wealthy people, he has used other websites to continue to spew his lies and madness, and I never thought that he'd be ruined after getting purged from YouTube because I've always known who he is. So, YouTube hasn't been occupying my mind for a long time. It never has occupied my mind much. Moreover, I’ve been experiencing such debilitating fatigue in the last year that I’ve been finding it difficult to speak and not really wanting to speak. Well, this is what can happen if you have a disease that always attacks your liver, your brain, your heart, and possibly (probably) your other internal organs. Therefore, my focus and energy have been so poor for the last several months that I haven’t even been able to spend much time on reading and researching, which is what I wanted to do. Well, this is really the story of my life because I’ve always had this disease. The worst thing about my disease is that there is no cure for it. Still, because of my reading, I’ve been able to find effective supplements that make me feel somewhat better, since I now know what this almost unknown disease is called, thanks to my reading of old medical books. I think that I will talk about these supplements in some future post. I finished reading Vasily Zubov’s ‘Leonardo da Vinci’ (1961) a few months ago, and I will quote from it now because I did highlight some, though not many, pages from it. “Often we find the word “ask” in Leonardo’s notebooks: “Ask Benedetto Portinari how the people go on the ice in Flanders”. “Ask the wife of Biagino Crivelli how the capon rears and hatches the eggs of the hen when he is in the mating season”. Leonardo turned to books with such questions, in order to get primary evidence on a question that occupied him, and he turned to them when he had just developed or thought through a viewpoint of his own. Leonardo’s notes are not only the fruit of his independent observations as a scientist and artist, but reveal the diversity of his reading. Solmi’s remarks are quite correct in this respect, although his studies of Leonardo’s sources are dated in places, especially where he skips over the intermediaries and has Da Vinci reading a number of Arab and ancient authors whose books would scarcely have been read by the great Italian scientist. Now let us take a close look at Leonardo da Vinci’s attitude toward the books he read, using as our example two works he definitely knew: Leon Battista Alberti’s three books on painting and ten books on architecture. We might say that as Leonardo read the books on painting, he entered into a conversation with the author. His notes and remarks are comments addressed to a collocutor. On comparing Leonardo’s texts with those of Alberti, we seem to be witnessing a dialogue, a metamorphosis and continual development of ideas, leading at times to a direct clash of opinions. That gives individual shadings to assertions which at first glance seem to be identical. Here is a notable example. Alberti spoke rather cursorily of the reflections of the faces of persons walking through a meadow: “We see in the faces of people that are walking over grass that they always have a greenish hue.” Leonardo spoke of the same thing in a much more specific and accurate manner: “If the surface of the ground near to her be meadows, and the woman be placed between a meadow lit by the sun and the sun itself, you will find that all the parts of the folds [of her dress] which are turned toward the meadow will be dyed by the reflected rays to the color of the meadow”. And, he states further: “that part [of the woman] which is exposed to the luminous air, through the weaving and penetrating of the sun’s rays, will tend toward blue, since the air is blue”. Vasari’s biography of Leonardo contains the following lines: “Philosophizing of natural things, he set himself to seek out the properties of herbs, going on even to observe the motions of the heavens, the path of the moon, and the courses of the sun.” In the first edition (1550) this is followed by the phrase: “That is why he formed in his mind a heretical view of things, not in agreement with any religion; evidently he preferred being a philosopher to being a Christian.” In the next edition (1568) he omitted this phrase, remarking that he had been poorly informed, but he could not reconcile things and left in his biography the story that Leonardo, on his deathbed, “asked to have himself diligently informed of the teaching of the Catholic faith, and of the good way and the holy Christian religion,” and that re repented of “how much he had offended God and mankind in not having worked at his art as he should have done.” It did not occur to Vasari that his picture of Leonardo’s deathbed repentance indirectly confirmed his earlier statement that throughout life Leonardo preferred to be a “philosopher.” The clarity of mind with which Leonardo approached faith in spirits is remarkable not only for this time, but for a much later period. It should not be forgotten that belief in magic continued to hold on stubbornly through the sixteenth century. One need but recall the names of Girolamo Cardano and Paracelsus." Even before I finished reading Zubov’s book, I finished reading ‘Michelangelo: His Life, His Times, His Era’ (1921) by Georg Brandes. I will quote from it too because I haven’t yet posted everything that I highlighted. “Both Leonardo and Michelangelo were poets. Michelangelo’s verses have come down to us, and they startle us with their blending of deep human passion and sophisticated reflection. He was at bottom a poet of solid competence, but there is too much that is labored in his considerable output. Surprisingly enough in a creative artist of swift decision, Michelangelo kept on revising, improving and polishing his verses; and equally surprising, Leonardo, working with infinite deliberation as an artist, making sketch after sketch before tackling a task, was an improviser par excellence as a poet. Accompanying himself on a lyra di braccio he had constructed himself, he was able to sing songs he made up on the spot. Il migliore dicitore di rime all improviso del tempo, he was called - the greatest lyric improviser of his time. We are in no position to judge Leonardo’s verses, for they have all been lost. We do know his prose. As for Michelangelo, his prose we know only from his letters, which deal for the most part with financial straits and family troubles. They have nothing to do with art, even though they may include an occasional emotional passage. Leonardo, however, was clearly a stylist. His description of a storm - the thrice-revised word picture of the Deluge - lives and breathes, reveals the talent of a painter and musician transmuted into words. Michelangelo’s poetry is introspective, marked now by the bitter irony, now by flaming pathos. Leonardo is preeminently thoughtful and lucid, as revealed in his fables and parables. Take the one about the butterfly that burns its wings: “Thou false light, how many hast thou not wretchedly deceived in days gone by, as thou hast deceived me! Were I meant to see the light, should it not then also be within my power to tell the sun from a miserable penny taper?” Leonardo’s minor poetic endeavors reflect the clarity of his mind, the serenity of his wisdom. Michelangelo at his best impresses with the power and fierceness of his style. In Milan, where he was drawn to the court of Ludovico il Moro, and where he later executed the collossal equestrian statue of Francesco Sforza - a glorification of the individual which democratic envy would have made impossible in Florence - a practical orientation prevailed, a striving for knowing and transforming reality, which may be properly designated as Aristotelian rather than Platonic. It is instructive that the name of Plato occurs but once in Leonardo’s five thousand manuscript pages, and on that occasion in a geometrical context, whereas he constantly cites Aristotle. Leonardo’s life was not solely devoted to the cultivation of art, but was spent in practical activities, scientific experiments and the observation of nature. In Milan he began the construction of canals equipped with ingenious locks of his own design. Toward the end of his life he proposed to Francis I the construction of a canal to join the rivers Sauldre and Morantin and to serve irrigation as well as navigation. He invented one machine after another, not merely numerous war devices, which can scarcely have been very practical, since otherwise they would have rendered Il Moro invincible, but countless appliances for peaceful purposes, from modest ones to serve everyday needs to highly ambitious ones. They included an ingenious pedometer, a rolling mill for iron, machines for making cylinders, files, saws, and drills, for cutting cloth, for planing and carding, a mechanical wine press, a goldbeater’s hammer, a ditch-digger, a wind-driven plow, a machine for drilling into the earth, a wheel for powering ships. He was not only the first to invent the screw propeller and to use a screw on a moving axle as a motor, but thought of using it in flight, built small paper models with thin steel propellers that could steer themselves. He invented a device for measuring the density of air. He was forever occupied with building different types of aircraft. He wrote a study on the flight of birds, constructed wings, flying chairs, gondolas for airships. He invented the parachute. “If a man have a tent of stiffened canvas,” he writes, “twelve ells wide and twelve ells long, he can plunge down from any height without fear.” Heat radiation is the object of his inquiries. He notes that rays passing through a glass globe filled with cold water are warmer than the fire whence they come, behaving much like rays reflected by a concave mirror. Leonardo understood steam power before anyone else did. He gives a careful description of a device he constructed to hurl a ball weighing one talent a distance of six stadia. All matters of mechanical construction came easily to him. He took the use of iron for cogwheels, beams, levers and rolls for granted, though it was quite rare at his time. He constantly pondered on how to replace hand work with machines. Leonardo understood before Copernicus that the earth revolves around the sun. He discovered the law of complementary colors before Chevreul. Before Pascal he perceived that water in two joined pipes always maintains the same level, whatever the form of the vessels. He studied cloud formation. Before the invention of telescopes, he recommended that eye glasses be made for seeing the moon larger (fa occhiali da vedere la luna grande). He was a passionate student of optics. He delved into the peculiarities of mirrors. He invented the camera obscura and explained its property of inverting images. He studied the nature of magnets. He invented the diving bell, but was reluctant to publish this invention, for fear, he said, that it might be used to commit murder under water. He studied acoustics as he did optics. He had a vague notion of radio communications, asserting that if holes were bored into the earth at two distant points, the human voice could be heard over great distances. He grasped the function of the heart and the circulation of the blood before anyone else did. He immersed himself into botany, found the rules by which leaves are arranged about a stalk and tested the effects of poisons on plants. Numerous drawings of plants from his hand, testify to his love of plant life. He had insight into geology before anyone else did. He protested that 5,288 years, given by the theologians of his time as the age of the earth, were not long enough. The banks of the Po, he insisted, showed alluvial deposits that would have required at least 200,000 years to accumulate. His geological studies led him to voice cautious doubt that there could have been anything like a general deluge. Seventy years before Bernard Palissy, founder of ceramics, who is regarded in France as the creator of geology, Leonardo laid the foundations of that science. Pondering the marine shells found high up in the mountains, he says: “These shells cannot have been carried there by the Deluge. They are all found at the same level, even though the mountain peaks are often still higher. If one believes that these molluscs, ordinarily found near the sea coast, began to move when the oceans swelled, then forty days of rain would not have been enough for these slow-moving creatures to traverse the distance of two hundred and fifty miles from the Adriatic coast to Montferrat.” He grasped that these shells had been deposited on the mountains by waters that had run off - something Voltaire failed to understand two-and-a-half centuries later. Leonardo declared, further, that the reflex movements of the limbs originated in the spinal cord rather than the brain. Like Michelangelo after him, he was a devoted anatomist. He had no patience with artists who, in revulsion before flayed and decomposing cadavers, shrank from obtaining insight into the structure and true character of the human body. Unlike Michelangelo, he concentrated on the influence of the emotions on the organs rather than on the interplay of muscles. Universal as he was, he strove to grasp the very essence of life. He found the source of life in movement (il moto e causa d’ogni vita) and here as in so many other areas anticipated the future. Among the many astonishing aspects of his genius is the fact that he left his manuscripts unpublished, indeed, made them difficult of access by employing mirror-writing, from right to left. He seems to have been entirely free of scientific ambition, for he allowed no one even to see his manuscripts.”