He who despairs of doctors is apt to abandon himself to charlatans. This has befallen those who have believed in the naturalistic laws of the beautiful. Artists sometimes adopt empirical canons, such as that of the proportions of the human body, or of the golden section, that is to say, of a line divided into two parts in such a manner that the less is to the greater as is the greater to the whole line (_be : ac = ac : ab_). Such canons easily become their superstitions, and they attribute to them the success of their works. Thus Michæl Angelo left as a precept to his disciple Marco del Pino da Siena that "he should always make a pyramidal serpentine figure multiplied by one two and three," a precept which did not enable Marco da Siena to emerge from that mediocrity which we can yet observe in many of his paintings that exist here in Naples. Others took Michæl Angelo's words as authority for the precept that serpentine undulating lines were the true _lines of beauty._ Whole volumes have been composed on these laws of beauty, on the golden section and on the undulating and serpentine lines. These should in our opinion be looked upon as the _astrology of Æsthetic._ XV THE ACTIVITY OF EXTERNALIZATION. TECHNIQUE AND THE THEORY OF THE ARTS [Sidenote: _The practical activity of externalization._] The fact of the production of physical beauty implies, as has already been remarked, a vigilant will, which persists in not allowing certain visions, intuitions or representations to be lost. Such a will must be able to act with the utmost rapidity and as it were instinctively, and may also need long and laborious deliberations. In any case, thus and thus only does the practical activity enter into relations with the æsthetic, that is to say, no longer as its simple accompaniment, but as a really distinct moment of it. We cannot will or not will our æsthetic vision: we can however will or not will to externalize it, or rather, to preserve and communicate to others, or not, the externalization produced. [Sidenote: _The technique of externalization._] This volitional fact of externalization is preceded by a complex of various kinds of knowledge. These are known as _technique,_ like all knowledge which precedes a practical activity. Thus we talk of an _artistic technique_ in the same metaphorical and elliptic manner that we talk of the physically beautiful, that is to say (in more precise language), _knowledge at the service of the practical activity directed to producing stimuli to æsthetic reproduction._ In place of employing so lengthy a phrase, we shall here avail ourselves of ordinary terminology, whose meaning we now understand.