After the first survey has been obtained, by the formation of the concepts of substance, "body" "ego" (matter, soul), the will is impelled to a more exact examination of the _changes_ that take place in this relatively permanent existence. The changeable element in bodies and in the ego, indeed, is the very thing that moves the will. Now, for the first time, do the constituent elements of the complex stand forth as properties of the same. A fruit is sweet; but it can also be bitter. So, too, other fruits can be sweet. The red color that is sought is found in many bodies. The neighborhood of some bodies is pleasant, that of others unpleasant. Thus, gradually, do different complexes appear to be composed of common constituent elements. The visible, the audible, the tangible, are separated from bodies. The visible is broken up into color and into form. Out of the manifold constitution of colors issue, again, in lesser numbers, certain other constituent elements—the primary colors, and so forth. The complexes are disintegrated into _elements_. III. The proper and useful habit of designating that which is permanent by a _single_ name, and of comprehending the same in a _single_ thought, without analysing at each operation its constituent parts, is liable to come into singular conflict with the tendency to separate these constituent parts. The obscure image formed of the permanent, which does not perceptibly change when one or another constituent part is taken away, appears to be something existent _by itself_. Inasmuch as it is possible to take away _singly_ every constituent part without effecting the capacity of the image formed to _represent_ the totality involved, or effecting its subsequent recognition, it is imagined that it is possible to take away _all_ these parts and yet have something remaining. Thus arises the monstrous idea of a _thing of itself_, different from, and incognisable with relation to, its "phenomenal" existence. Thing, body, matter, are nothing apart from this complex of colors, sounds, and so forth—apart from their so-called marks, or characteristics. That Protean, illusory philosophical problem of a _single_ independent thing with _many_ properties, arises from the misunderstanding of the fact, that extensive comprehension and accurate separation, although both are temporarily justifiable and profitable for a number of purposes, can not and must not be employed _simultaneously_. A body is _single_ and unchangeable so long as it is not required to take details into consideration. Thus both the earth and a billiard ball are _spheres_ so long as we disregard all minor deviations from the spherical form, and greater exactitude is not necessary. But if we are compelled to carry on investigations in orography or microscopy both bodies cease to be spheres. IV.