This is intended to be a book about Leonardo's intellectual and artistic life as a whole. I have endeavoured to capture the unity of his creative intellect, not I hope at the expense of his variousness, but in such a way as to illustrate the main trunk from which the ramifications of his work grew. I have attempted to come to terms with the principles, style, and development of his thought, rather than enumerating his artistic and scientific achievements. I have been concerned to characterize the shape of his vision of the world, to assess the relationship between this vision and his works of art, and to show how each major facet of his activity relates to the whole and how his outlook developed during the full span of his career.
This approach inevitably places an emphasis upon those aspects of his work that possess the clearest philosophical implications, and militates against an extended consideration of his technical work in all its inventive variety. I have, in other words, been concerned with the principles of his mechanics rather than with a list of the machines he invented. I have been concerned with the reasons why his anatomies took the form they did, rather than running him beside Vesalius and Harvey in a historical race towards 'observational accuracy'. I have been concerned to understand his theory of vision and its implications rather than trying to mould him into an ancestor of Kepler. I have been concerned to illustrate the personal flavour that he brought to a broadly Aristotelian range of physical sciences rather than to draw up an historical balance sheet of scientific credits and debits. And ultimately, I have been concerned to show how his art profoundly reciprocates his scientific vision but is not identical to it.
Just as it would be idiotic to claim that this or any other volume was the comprehensive Leonardo book, so it would be misleading to think that the internal balance of this necessarily selective study reflects the actual balance of the various activities in his own career. There are a number of reasons why such a balance remains elusive. The most unavoidable is that the surviving historical record is incomplete in a lopsided manner, as we will have repeated cause to see. It appears likely that about four-fifths of his written output is lost. Furthermore, any selection of material from his legacy is inevitably conditioned by the author's personal attitude to what he considers important, interesting, and relevant to his theme. Finally, it is doubtful if anyone could achieve the required level of understanding across the whole range of Leonardo's work to treat every