In the same way, all those other aspects of the universe which are "animate" but sub-human, such as grass, moss, lichen, plants, sea-weed, trees, fish, birds, animals and the like, must be regarded as sharing in a still more intimate sense in this unfathomable struggle. This conception has a double element of truth. For not only do these things depend for their form and shape and reality upon the complex vision of the soul which contemplates them; but they are themselves, since they are things endowed with life, possessed of some measure or degree of the complex vision. And if the souls of men and the Souls of the "sons of the universe" are inextricably made up of the very stuff of this unfathomable struggle, between life and what resists life, we cannot escape from the conclusion that the souls of plants and birds and animals and all other living things are inextricably made up of the stuff of the same unfathomable struggle. For where there is life there must be a soul possessed of life. Life, apart from some soul possessed with life, is an abstraction of the logical reason and a phantom of no more genuine reality than the "a priori unity of apperception" or "the universal self-conscious monad." What we call reality, or the truth of the system of things, is nothing less than an innumerable company of personalities confronting an objective mystery; and while we are driven to regard the "inanimate," such as earth and air and water and fire, as the bodily expressions of certain living souls, so are we much more forcibly driven to regard the "animate," wherever it is found, as implying the existence of some measure of personality and some degree of consciousness. Life, apart from a soul possessing life, is not life at all. It is an abstraction of the logical reason which we cannot appropriate to our instinct or imagination. A vague phrase, like the phrase "life-force," conveys to us whose medium of research is the complex vision, simply no intelligible meaning at all. It is on a par with the "over-soul"; and, to the philosophy of the complex vision, both the "life-force" and the "over-soul" are vague, materialistic, metaphorical expressions which do not attain to the dignity of a legitimate symbolic image. They do not attain to this, because a legitimate symbolic image must appeal to the imagination and the aesthetic sense by the possession of something concrete and intelligible. Any individual personal soul is concrete and intelligible. The personal souls of "the sons of the universe" are concrete and intelligible. But the "over-soul" and the "life-force" are neither concrete nor intelligible and therefore cannot be regarded as legitimate symbols. One of the most important aspects of the method of philosophical enquiry which the philosophy of the complex vision adopts is this use of legitimate symbolic images in place of illegitimate metaphorical images.