A man standing upright, with his arms extended, is, as Leonardo da Vinci has shown, enclosed in a square, the extreme extent of his arms being equal to his height. This is evidently the most general measure of the latter kind. Of the latter kind, also, is Camper's ellipsis for measuring the relative size of the shoulders in the male, and the pelvis in the female. So also is the measure from the centre of one mammæ to that of the other, as equal to the distance from each to the pit over the breast-bone. We now approach the chief difficulty, which evidently formed a stumbling-block even to Leonardo da Vinci--that HARMONIC METHOD which, strange as it may appear, will be found to afford rules that are at once perfectly _precise_, and yet infinitely _variable_. The apparent impossibility indeed of such a rule seems to have embarrassed every one. And the statement which Bossi makes in regard to Leonardo da Vinci, in this respect, is exceedingly interesting. "He thought," says Bossi, "but little of any general measure of the species; and that _the true proportion_ admitted by him, and acknowledged to be of difficult investigation, is solely _the proportion of an individual in regard to himself_, which, according to true imitation, should be _different in all the individuals of a species_, as is the case in nature. Thus, says he, '_all the parts of any animal should correspond with the whole_; that which is short and thick, should have every member short and thick; that which is long and thin, every member long and thin; and that which is between the two, members of a proportionate size.' From this and other precepts, it follows, that, when he speaks of proportion, he is to be understood as referring to the _harmony of the parts of an individual_, and not to the general rule of imitation in reference to dimensions."--How clearly (notwithstanding the error as to _all_ being short and thick) does this point to the harmonic method of proportion forthwith to be explained? "It would seem he felt within himself that he did not reach the perfection of those wonderful ancients of whom he professed himself the admirer and disciple. "It became, therefore, Leonardo's particular care and study to approach as nearly as he could to the ancients in the true imitation of beautiful nature under the guidance of philosophy. "But whether from want of great examples, or from not sufficiently penetrating, as he himself thought, into these artifices, or from comprehending them too late, he modestly laments that he did not possess the ancient art of proportions. He then protests that he has done the little he was able to do, and asks pardon of posterity that he has not done more. Such are the sentiments that Platino exhibits in the following epitaph: "Leonardus Vincia (sic) Florentinus Statuarius Pictor que nobilissimus de se parce loquitur.