We contend, however, that the fact does not prove the existence of the reality named the sun's ray beyond or behind the white light, nor its existence beyond or behind the spectrum. It is evident that the reality exists in white light, and that it is known as the white light when it goes through a pane of glass; and that the same reality exists in the spectrum, and is known as the spectrum when it goes through the prism. The reality is known as the white light on the one hand, and as the spectrum on the other. It is not unknowable, but knowable. Suppose that one and the same reality exhibits one aspect when it stands in relation to another object; two aspects when it stands in relation in two different objects; three aspects when it stands in relation to three different objects. The reality of one aspect never proves the unreality of another aspect, for all these three aspects can be equally real. A tree appears to us as a vegetable; it appears to some birds as a shelter; and it appears to some worms as a food. The reality of its aspect as a vegetable never proves the unreality of its aspect as food, nor the reality of its aspect as food disproves the reality of its aspect as shelter. The real tree does not exist beyond or behind the vegetable. We can rely upon its reality, and make use of it to a fruitful result. At the same time, the birds can rely on its reality as a shelter, and build their nests in it; the worms, too, can rely on its reality as food, and eat it-to their satisfaction. A reality which appears to me as my wife must appear to my son as his mother, and never as his wife. But the same real woman is in the wife and in the mother; neither is unreal. 15. Thing-in-Itself means Thing-Knowerless. How, then, did philosophers come to consider reality to be unknowable and hidden behind or beyond appearances? They investigated all the possible presentations in different relationships, and put them all aside as appearances, and brooded on the thing-in-itself, shut out from all possible relationship, and declared it unknowable. Thing-in-itself means thing cut off from all possible relationships. To, put it in another way: thing-in-itself means thing deprived of its relation to its knower--that is to say, thing-knower-less. So that to declare thing-in-itself unknowable is as much as to declare thing-unknowable unknowable; there is no doubt about it, but what does it prove?