Our _extremes_ thus placed, now imagine the Atlas throwing off by degrees, certain portions of bone and muscle, proper for the attainment of light agility, as if aiming at the Mercury's airy form and quality, whilst on the other hand, see the Mercury augmenting his taper figure by equal degrees, and growing towards an Atlas in equal time, by receiving to the like places from whence they came, the very quantities that the other had been casting off, when, as they approach each other in weight, their forms of course may be imagined to grow more and more alike, till at a certain point of time, they meet in just similitude; which being an exact medium between the two extremes, we may thence conclude it to be the precise form of exact proportion, fittest for perfect active strength or graceful movement; such as the Antinous we proposed to imitate and figure in the mind[9]. [9] The jocky who knows to an ounce what flesh or bone in a horse is fittest for speed or strength, will as easily conceive the like process between the strongest dray-horse and the fleetest racer, and soon conclude, that the fine war-horse must be the medium between the two extremes. I am apprehensive that this part of my scheme, for explaining exact proportion, may not be thought so sufficiently determinate as could be wished: be this as it will, I must submit it to the reader, as my best resource in so difficult a case: and shall therefore beg leave to try to illustrate it a little more, by observing, that, in like manner, any two opposite colours in the _rainbow_, form a third between them, by thus imparting to each other their peculiar qualities; as for example, the brightest yellow, and the lively blue that is placed at some distance from it, visibly approach, and blend by interchangable degrees, and, as above, _temper_ rather than destroy each other's vigour, till they meet in one firm compound; whence, at a certain point, the sight of what they were originally, is quite lost; but in their stead, a most pleasing green is found, which colour nature hath chose for the vestment of the earth, and with the beauty of which the eye is never tired. From the order of the ideas which the description of the above three figures may have raised in the mind, we may easily compose between them, various other proportions. And as the painter, by means of a certain order in the arrangement of the colours upon his pallet, readily mixes up what kind of tint he pleases, so may we mix up and compound in the imagination such fit parts as will be consistent with this or that particular character, or at least be able thereby to discover how such characters are composed, when we see them either in art or nature.