The career of Leonardo da Vinci must be the most intimidating subject in the history of art. The paintings and preparatory drawings are a major topic in themselves, and any monograph on Leonardo the artist invites comparison with Kenneth Clark’s classic study, one of the best books of its type. Then there are the notebooks, a written legacy unparalleled in scale and range among surviving records of the Renaissance. The secondary literature is no less formidable, even excluding the many banal hagiographies and such eccentricities as the tedious claims of collectors to possess the original Mona Lisa. Simply to consult the facsimile of Leonardo’s largest manuscript, the aptly named Codex Atlanticus, in 12 vast and unwieldy volumes with an equally extensive commentary, is a major undertaking. Moreover, the recent scholarship on Leonardo, often of high quality, abounds with detailed observations and a mass of cross-references to one codex or another, but contains much less in the way of synthesis. To come to terms with this material requires not just time, but also the energy to master a whole range of subjects quite outside the bounds of conventional art history.
The sheer size of the notebooks is daunting enough. They amount to some two thousand pages, mostly covered with densely-packed jottings in mirror writing. Fortunately these texts have all been transcribed. The problem is to impose some kind of order on their content, since they are exactly what their name implies, a series of notes, often random and disorganised. Leonardo himself frequently recorded that he had begun a new book on some topic, but in practice any scheme that he may have had which involved arranging his thoughts in a coherent way was always abandoned after a few pages. It is no accident that the most carefully organised body of his statements on any subject, the so-called Treatise on Painting, preserved in a manuscript in Rome, is actually the work of an exceptionally diligent and knowledgable follower who went through the master’s papers collecting what he thought relevant. Despite his truly heroic efforts the result is still very far from a proper treatise; and it is a sobering thought that three-quarters of the material he transcribed cannot be found in Leonardo’s extant writings. What we know today, extensive as it is, must be no more than a fragment of what he set down.
The character of the notebooks makes it extraordinarily difficult to establish Leonardo’s views on any subject. To do so involves making a synthesis of countless scattered remarks, though the task has admittedly been simplified by the researches of Carlo Pedretti and others on the chronology of the manuscripts. Moreover, there is always a temptation to minimise the essentially inconclusive and speculative character of Leonardo’s observations. One has to reconstruct his habits of thought rather than his theories, which were usually in a state of flux. There is also the more serious danger of crediting Leonardo with an originality which is largely unjustified. Much of his scientific work was an attempt to master an existing body of knowledge to which he had incomplete access. His knowledge of Latin was at best rudimentary, so he had to extract what he could from popularising texts in the volgare. Leonardo’s disparaging remarks about established ideas are for this reason frequently defensive in tone, as well as misleading about his attitude to ancient authorities. Time and again, as Kemp points out, he made problems for himself by failing to take adequate account of observations and arguments available in standard Classical sources.
The question of Leonardo’s originality arises most obviously and most acutely in connection with his many drawings of machines. Other visual records of Renaissance technology are very uncommon, so one often cannot establish whether he was simply recording existing devices, proposing modifications of some kind, or even producing entirely new inventions of his own. With any other artist the issue might be resolved by considering the actual character of the illustration, but with Leonardo this is impossible. So remarkable was his ability to visualise the most complex machines in three dimensions that he could make a finished drawing in perfect perspective, without the least uncertainty or ambiguity, as if he had the object before his eyes. He would even add little sketches to demonstrate the detailed operation of specific features. In the same way his early anatomical studies look like the product of direct observation, although they include things which do not exist in nature.
Even the relatively restricted topic of his career as a professional painter and sculptor raises endless problems. None of his sculpture can be shown to have survived, and so far as is known none of it was ever finished, apart from the full-size clay model for the equestrian monument to Francesco Sforza. Our knowledge of his work in this medium is therefore restricted to preliminary drawings. The paintings, too, present some intractable difficulties, particularly in connection with their chronology. For example, there exist two versions of The Virgin of the Rocks, but the numerous documents about the commission do not fully explain the circumstances in which they were produced. The recent discovery, reported in the press, of yet another document seems to make the whole matter still more obscure. Similarly, estimates of the date of the Mona Lisa range over a decade, and even the identity of the sitter is controversial. The traditional title is derived from Vasari, who said that Leonardo painted the wife of Francesco del Giocondo, but a slightly earlier writer referred instead to a portrait of Francesco himself – which this clearly is not. These two authors seem to have used a common source, but it is impossible to say which of them transcribed the text correctly. Again, the two early descriptions of compositions by Leonardo on the theme of the Virgin and Child with St Anne are not only inconsistent with one another, but also incompatible with the painting in the Louvre and the cartoon in the National Gallery. Only one of Leonardo’s easel paintings, in fact, can be precisely dated.
Most of the recent work on Leonardo has been concerned with specific issues, but Kemp has bravely undertaken a survey of virtually the whole range of his output. He has succeeded brilliantly, producing a book that is scholarly, readable and full of original insights. The opening chapter, appropriately entitled ‘Leonardo da Firenze’, is devoted to the artist’s activity up to his departure for Milan about 1482, at the age of 30. The focus here, inevitably, is on Leonardo’s work as a painter, since no notebooks survive from this period. But Professor Kemp demonstrates very well that the artistic milieu in which Leonardo grew up would have encouraged him to extend his horizons beyond the normal preoccupations of a practising craftsman. He was certainly not the first Florentine artist to concern himself with science and technology. Such interests were shared, for example, by Brunelleschi and Ghiberti, as well as by the Sienese Francesco di Giorgio, and they would have been fostered by his teacher Verrocchio, whose output embraced both painting and sculpture in addition to more ephemeral products such as decorations for tournaments. But whereas all these artists combined a theoretical cast of mind with an entirely practical ability to produce finished works of art, from the first Leonardo seems to have been temperamentally unsuited to earning a living in a competitive market. The long sequence of commissions accepted and then abandoned begins very early in his career.
It is usually thought that a desire for financial security was the main reason for Leonardo’s surprising decision to seek employment at the court of Milan, where he remained for 18 years. Kemp divides this phase of his career into two chapters, one devoted mainly to Leonardo’s work as a painter and sculptor, the other to his scientific investigations. He characterises this period as exceptionally productive, but in specifically artistic terms this is hardly true. A rather small altarpiece, a handful of portraits, the decoration of the Sala delle Asse in the Castello Sforzesco, The Last Supper and the clay horse certainly do not constitute a large body of work for a 15th-century artist. Indeed, it is something of a mystery how Leonardo persuaded his patron to provide him with an evidently comfortable income. Some of his energy, certainly, was employed in staging court entertainments, but it is difficult to believe that he could ever have found such work entirely congenial, given his notorious reluctance to bring anything to a conclusion. In these years much of his time must have been occupied by his attempts to assimilate the scientific knowledge of his day, ranging over a far wider field than any of his predecessors in Florence. It was a Renaissance commonplace that painters, like poets, needed encyclopedic learning, but Leonardo seems to have been the first to have seriously tried to live up to this ideal. Some of his research, notably his studies of machinery for industry and warfare, may have seemed to the Duke to have a practical application. There is no evidence, however, that any of his proposals were actually carried out. Leonardo’s greatest assets as a court artist, evidently, were his famous wit – the aspect of his genius most difficult to appreciate today – and his ability, principally by means of his matchless drawings, to make the wildest schemes seem plausible.
This side of his personality is illustrated by Vasari’s anecdote about his project for raising the Florentine Baptistery and placing steps underneath. Leonardo explained his proposals so eloquently to the leading citizens that only after his departure did they realise the idea was quite impractical. This episode must have occurred during Leonardo’s second period in Florence, which lasted, with interruptions, from 1500 to 1508, and which is the subject of Kemp’s fourth chapter. At this time he worked on various versions of The Virgin and Child with St Anne and began the Leda, the Mona Lisa and the gigantic mural of The Battle of Anghiari. To a contemporary it seemed that Leonardo’s interest in geometry was interfering with his work as a painter, but he certainly painted much more than he had ever done in Milan.
The last chapter is devoted to Leonardo’s final years in Milan, Rome and France, which were marked by a renewed preoccupation with science. But now, as Professor Kemp demonstrates, Leonardo became uncomfortably aware of the inadequacy of many of his earlier ideas. In the study of anatomy he was increasingly conscious of the discrepancies between the observed facts and the traditional theories, just as he recognised the shortcomings of Renaissance conventions of perspective. Most important of all, he lost his old confidence in the close structural analogy between the microcosm, man, and the macrocosm, the world. Nonetheless, Leonardo retained his belief that all physical phenomena were ultimately explicable in terms of natural laws based on mechanical principles. He continued his researches with undiminished energy, and his studies of the movement of water in the Codex Leicester (now Hammer) comprise the most systematic body of work in any of the notebooks. Even if at this stage, as in his earlier years, firm conclusions usually remained beyond Leonardo’s grasp, the sustained effort that he devoted to his investigations remains one of the most impressive achievements of the Renaissance.
It is easy enough to appreciate this now that we can read the notebooks. But it is equally easy to understand why Leonardo’s contemporaries should so often have felt that he had squandered his talents. Virtually all that Vasari has to say, for example, about his time in Rome concerns the tricks and curiosities he devised to amuse the Papal Court – the hollow birds made of wax which flew when they were blown up with air, the inflated bladder which filled a large room. Such toys certainly serve to modify the impression one sometimes gets of a man constantly engaged in profound study of the physical world. Yet the notebooks, too, give plenty of evidence of Leonardo’s obsession with gadgetry and trivia.
Kemp does not place much emphasis on this more fanciful side of Leonardo’s character and is particularly concerned to correct the conventional view that his interests were increasingly divorced from the practice of his art. As he puts it: Those authors who have written that Leonardo began by studying things as an artist but increasingly investigated things for their own sake have missed the point entirely. What should be said is that he increasingly investigated each thing for each other’s sake, for the sake of the whole and for the sake of the inner unity, which he perceived both intuitively and consciously.’ This is certainly true, but the fact remains that the relationship between Leonardo’s painting and his scientific studies underwent a profound modification. Early in his career his investigations were directly related to his work as a painter and engineer, a profession closely connected in the Renaissance with the practice of the visual arts, especially architecture. But as he grew older Leonardo came increasingly to regard his art as a subordinate aspect of a more broadly based inquiry into the natural world, even though until the end of his life the subjects he chose to study tended to be determined at least in part by his aesthetic preoccupations.
Leonardo’s early attitudes can be illustrated very well by a picture like The Virgin of the Rocks in the Louvre. This already incorporates his characteristic innovations of chiaroscuro and very subtle tonal transitions, or sfumato – qualities that were increasingly emphasised in his later work. But whereas he very soon began to provide theoretical justification for this kind of painting, it is easier to see the origins of the new style in the familiar Renaissance controversy about the relative merits of painting and sculpture, rather than in scientific experiments in optics. What Leonardo was trying to do, in fact, was to create an impression of relief, one of the most admired qualities in a picture, by explicitly non-sculptural means. In this respect, he was polemically reacting against the traditional Florentine emphasis on expressive outline, and the same attitude must underly his very unusual reluctance to use the medium of fresco.
The Virgin of the Rocks can be understood entirely within the context of Florentine painting, but a later work like the Mono Lisa cannot. Kemp recognises that this is not a portrait in the conventional sense, but primarily an illustration of Leonardo’s theory about the relationship between the microcosm and the macrocosm, with the landscape shown as an organism subject to the same kind of physical processes as the figure itself. Its status, however, is very different from that of the drawings in the notebooks. It is an elaborate visual statement about ideas concerning the nature of the physical world, and for Leonardo its validity as a work of art must in part at least have been dependent on the truth of these ideas. As one might expect, contemporaries did not see the picture in quite this way. Other artists adopted the formal innovations, such as the pose of the figure, while Leonardo’s attempt to change the premises and function of painting found no following.
Professor Kemp, quite rightly, is concerned to judge Leonardo on his own terms, even though he sometimes cannot avoid a note of impatience. He has much that is persuasive and new to say about the paintings – for example, in his interpretation of the Sala delle Asse – but the emphasis of the book is on the scientific investigations. Here he is notably successful, securely relating Leonardo’s thought to the intellectual traditions of his day. But his place in the world of Renaissance art remains in certain respects unclear. There is no great problem about the early Florentine period, but when he moves to Milan he seems to enter an artistic vacuum; like every other book on the subject, Kemp’s text is here virtually devoid of references to contemporary painting and sculpture. How much artists of the 16th century knew of his mature work is also difficult to establish, since the murals rapidly deteriorated and most of the other paintings soon found their way to France. The immediate impact of Leonardo was in areas which were not central to his own concerns – the treatment of narrative, the manner of working out compositions, and the partial adoption of his chiaroscuro and sfumato. The full range of his achievement, both as artist and as scientist, must have remained to a great degree hidden. In his remarkable book Martin Kemp has succeeded in revealing Leonardo’s genius with unprecedented clarity, so that we can now see him in a way that was never possible before.