There are, also, no individual cases in nature; all particular cases are the expression and effect of a law. And the fact, now unquestioned, that certain great men of genius have been insane, permits us to presume the existence of a lesser degree of psychosis in other men of genius. But, adds Joly, genius is often precocious; as Raphael at fourteen years of age, Mozart at six, Michelangelo at sixteen; and sometimes it is tardy, with special characteristics, as in Alfieri. This is true; precocious originality is one of the characteristics of genius; but precisely because genius is a neurosis, an accidental circumstance may provoke it even at a comparatively late age, and like every neurosis which depends on irritation of the cerebral cortex it may take on different aspects, according to the spot attacked, while preserving the same nature. Hailes, in a much praised essay on genius in art, maintains that genius is a continuation of the conditions of ordinary life; thus, as we all write prose we must all have a little genius. But how then does it happen, Brunetière rightly objects,[4] that one individual alone becomes a great painter or a great poet? And how is it that so many philosophers affirm, and quite truly, that genius consists in an exaggerated development of one faculty at the expense of others? The man of genius is a monster, say others. Very well, but even monsters follow well-defined teratologic laws. Brunetière remarks that there have been men of talent, like Addison and Pope, who were lacking in genius; and men of genius, like Sterne, who were lacking in talent. These two facts, however, are not contradictory; to be lacking in talent, or rather in good sense or common sense, is one of those characters of genius which witness to the presence of neurosis, and indicate that hypertrophy of certain psychic centres is compensated by the partial atrophy of other centres. As to the first assertion, it confirms rather than destroys my conclusions. Certainly talent is not genius, just as vice is not crime, but there is a transition from one to the other in virtue of that law of continuity which may be observed in all natural phenomena. _Natura non facit saltus._ I must confess here that very often in this book I have had to confound genius with talent; not because they are not quite distinct, but because the line that separates them, like that which separates vice from crime, is very difficult to define. A man of scientific genius, lacking in education and opportunities--a Gorini, for example--will appear more sterile than a man of talent, who has been favoured by circumstances from the first.