§ 3. I. SPRING: or the appearance of elastic and progressive power, as opposed to that look of a bent piece of cord.--This follows partly on the poise of the bough, partly on its action in seeking or shunning. Every branch-line expresses both these. It takes a curve accurately showing the relations between the strength of the sprays in that position (growing downward, upward, or laterally), and the weight of leaves they carry; and again, it takes a curve expressive of the will or aim of those sprays, during all their life, and handed down from sire to son, in steady inheritance of resolution to reach forward in a given direction, or bend away from some given evil influence. And all these proportionate strengths and measured efforts of the bough produce its loveliness, and ought to be felt, in looking at it, not by any mathematical evidence, but by the same fine instinct which enables us to perceive, when a girl dances rightly, that she moves easily, and with delight to herself; that her limbs are strong enough, and her body tender enough, to move precisely as she wills them to move. You cannot say of any bend of arm or foot what precise relations of their curves to the whole figure manifest, in their changeful melodies, that ease of motion; yet you feel that they do so, and you feel it by a true instinct. And if you reason on the matter farther, you may know, though you cannot see, that an absolute mathematical necessity proportions every bend of the body to the rate and direction of its motion; and that the momentary fancy and fire of the will measure themselves, even in their gaily-fancied freedom, by stern laws of nervous life, and material attraction, which regulate eternally every pulse of the strength of man, and every sweep of the stars of heaven. § 4. Observe, also, the balance of the bough of a tree is quite as subtle as that of a figure in motion. It is a balance between the elasticity of the bough and the weight of leaves, affected in curvature, literally, by the growth of _every_ leaf; and besides this, when it moves, it is partly supported by the resistance of the air, greater or less, according to the shape of leaf;--so that branches float on the wind more than they yield to it; and in their tossing do not so much bend under a force, as rise on a wave, which penetrates in liquid threads through all their sprays. [Illustration] [Illustration: 57. Leafage by Durer and Veronese.] [Illustration: FIG. 56. _To face page 65._]