Moreover, since man is composed of mind _and_ body, both reciprocally and most intimately related to each other--since his mentality is manifested only by bodily organs, and the latter depends wholly upon the former, of course his mind can be studied only through its ORGANIC relations. If it were manifested independently of his physiology, it might be studied separately, but since all his organic conditions modify his mentality, the two must be studied TOGETHER. Heretofore humanity has been studied by piece-meal. Anatomists have investigated only his organic structure, and there stopped; and mental philosophers have studied him metaphysically, wholly regardless of all his physiological relations; while theologians have theorized upon his moral faculties alone; and hence their utter barrenness, from Aristotle down. As if one should study nothing but the trunk of a tree, another only its roots, a third its leaves, or fruit, without compounding their researches, of what value is such piecemeal study? If the physical man constituted one whole being, and the mental another, their separate study might be useful; but since all we know of mind, and can do with it, is manifested and done wholly by means of physical instruments--especially since every possible condition and change of the physiology correspondingly affects the mentality--of course their MUTUAL relations, and the laws of their RECIPROCAL action, must be investigated _collectively_. Besides, every mental philosopher has deduced his system from his own closet cogitations, and hence their babel-like confusion. But within the last half century, a new star, or rather sun, has arisen upon the horizon of mind--a sun which puts the finger of SCIENTIFIC CERTAINTY upon every mental faculty, and discloses those _physiological_ conditions which affect, increase or diminish, purify or corrupt, or in any other way modify, either the mind itself, or its products--thought, feeling, and character--and thereby reduces mental study to that same _tangible_ basis of _proportion_ in which all science consists; leaving nothing dark or doubtful, but developing the true SCIENCE OF MIND, and the laws of its action. Of this, the greatest of all discoveries, Gall was the author, and Phrenology and Physiology the instruments which conjointly embrace whatever appertains to mind, and to man, in all his organic relations, show how to perfect the former by improving the latter, and disclose specific SIGNS OF CHARACTER, by which we may know ourselves and our fellow-men with certainty--a species of knowledge most delightful in acquisition, and valuable in application. 2.--STRUCTURE CORRESPONDS WITH CHARACTER.