His passion for finding things out

I have said that Leonardo's earliest notebooks are chiefly concerned with technical matters, and that a number of entries are no more than a record of ingenious devices. But almost from the first, Leonardo's penetrating grasp of construction, combined with his restless curiosity, gave his notes on technical matters a more general value. He was not content to record how a thing worked: he wished to find out why. It is this curiosity which transformed a technician into a scientist. We can watch the process at work in the manuscripts. First, there are questions about the construction of certain machines, then, under the influence of Archimedes, questions about the first principles of dynamics; finally, questions which had never been asked before about winds, clouds, the age of the earth, generation, the human heart. Mere curiosity has become profound scientific research, independent of the technical interest which had preceded it. In this gradual change of attitude towards the objects of his curiosity Leonardo showed himself a marvel of self-education. He had received the ordinary training of a poor boy in Florence, practically confined to reading, writing and that characteristically Florentine instrument of education, the abacus; and at an early age he was apprenticed to Verrocchio. Nothing in his education can have prepared him to wrestle with the crabbed and tortuous encyclopedias in which the scientific knowledge of antiquity was embalmed. Yet the notebooks give evidence of very wide reading. They are full of reminders to borrow or consult books, and research has shown how many passages, which used to be taken as original discoveries, are copied word for word from other authors. The turning-point in this process of self-education--we may almost say in Leonardo's life--was the period about the year 1494 in which he taught himself Latin. We have evidence of this process in two manuscripts, H and the Trivulzian, into which he has copied out almost the whole of a contemporary Latin Grammar by Niccolò Perotti, and a large part of a Latin Vocabulary by Luigi Pulci. At that date few of the scientific writings of the ancients were accessible in the vulgar tongue. In particular the works of Archimedes, which, as Séailles rightly pointed out, were the greatest single influence on Leonardo's thought, seem to have existed only in Latin translations. We can imagine how this new key to the mysteries of nature made Leonardo, as contemporaries describe, impacientissimo del penello, out of all patience with his brush.

Love of learning alone does not account for the contents, still less the form of Leonardo's notebooks. His passion for finding things out was accompanied by a far less profitable passion for writing them down. His notebooks are like the result of a Chinese examination in which, as we are told, the examinee is placed in a room alone and asked to write down all he knows; and in part they are little more than commonplace books-selections from his reading, often of the most unexpected kind. He seems to have enjoyed exposition. He wished his demonstrations to be perfectly clear and unmistakable, and repeats his proofs from every angle so that all contradiction is impossible. He also repeats the same demonstration several times in different parts of the manuscripts, rather than risk an unsupported statement. This thoroughness is an essential characteristic of his mind, and he defends it in a passage which may well make the author of a brief study of Leonardo pause in embarrassment.

Abbreviations do harm to knowledge and to love, seeing that the love of anything is the offspring of this knowledge, the love being the more fervent in proportion as the knowledge is more certain. . . . Of what use, then, is he who abridges the details of those matters of which he professes to give thorough information, while he leaves behind the chief part of the things of which the whole is composed? It is true that impatience, the mother of stupidity, praises brevity, as if such persons had not life long enough to serve them to acquire a complete knowledge of one single subject, such as the human body; and then they want to comprehend the mind of God in which the universe is included, weighing it minutely and mincing it into infinite parts, as if they had to dissect it!

A result of this characteristic was his dislike of general principles. Rather than risk a formula he would repeat a proof many times for each particular instance, and it was only this lack of synthetic power which prevented him from anticipating many of the discoveries of later scientists, amongst them the circulation of the blood. The only form of abstraction, which he allowed himself--and it is safe to say that he did not recognise it as such--was mathematics. "The man who blames the supreme certainty of mathematics feeds on confusion and can never silence the contradictions of sophistical sciences which lead to interminable conflict." "There is no certainty in sciences when mathematics cannot be applied." These and similar pronouncements are to be found throughout the manuscripts, and show that to Leonardo mathematics were not simply a convenient means of measuring his researches. They were an article of belief. It is significant that the certainty of mathematics is more than once contrasted with the uncertainty of theological discussions. 1 Living on the eve of the Reformation, Leonardo seems to have anticipated the futility of religious conflicts, and to have held that new faith in mathematical science, which in the seventeenth century was to replace, in the finest minds, the lost certainties of revealed religion. This does not mean that Leonardo was a great mathematician. To him figures were the most incontrovertible of facts, and facts were good in themselves. They should not be made to create hypotheses. He therefore used mathematics as a means of proof rather than as a technique of speculation; and it must be confessed that he also used them in those games and puzzles on which so many early mathematicians wasted their abilities.