Chapter IV (part 1)

p. 38 CHAPTER IV In what direction may the fourth dimension lie? What is motion? Two kinds of motion—motion in space and motion in time—which are contained in every movement. What is time? Two ideas contained in the conception of time. The new dimension of space, and motion upon that dimension. Time as the fourth dimension of space. Impossibility of understanding the fourth dimension without the idea of motion. The idea of motion and the "time-sense." The time-sense as a limit (surface) of the "space-sense." Hinton on the law of surfaces. The "ether" as a surface. Riemann's idea concerning the translation of time into space in the fourth dimension. Present, past, and future. Why we do not see the past and the future. Life as a feeling of one's way . Wundt on the subject of our sensuous knowledge. WE have established by a comparison of the relation of lower dimensional figures to higher dimensional ones that it is possible to regard a four-dimensional body as the tracing of the motion of a three-dimensional body upon the dimension not contained in it; i.e., that the direction of the motion upon the fourth dimension lies outside of all the directions which are possible in three-dimensional space. But in what direction is it? In order to answer this question it will be necessary to discover whether we do not know some motion not confined in three-dimensional space. We know that every motion in space is accompanied by that which we call motion in time . Moreover , we know that everything existing, even if not moving in space, moves eternally in time. And equally in all cases, whether speaking of motion or absence of motion, we have in mind an idea of what was before, what now becomes, and what will follow after. In other words, we have in mind the idea of time. The idea of motion of any kind, also the idea of absence of motion, is indissolubly bound up with the idea of time. Any motion or absence of motion proceeds in time and p. 39 cannot proceed out of time. Consequently, before speaking of what motion is, we must answer the question, what is time? Time is the most formidable and difficult problem which confronts humanity. Kant regards time as he does space: as a subjective form of our receptivity; i.e., he says that we create time ourselves, as a function of our receptive apparatus, for convenience in perceiving the outside world. Reality is continuous and constant, but in order to make possible the perception of it, we must dissever it into separate moments; imagine it as an infinite series of separate moments out of which there exists for us only one. In other words, we perceive reality as if through a narrow slit, and what we are seeing through this slit we call the present; what we did see and now do not see—the past; and what we do not quite see but are expecting—the future. Regarding each phenomenon as an effect of another, or others, and this in its turn as a cause of a third; that is, regarding all phenomena in functional interdependence one upon another, by this very act we are contemplating them in time, because we picture to ourselves quite clearly and precisely first a cause, then an effect; first an action, then its function; and cannot contemplate them otherwise. Thus we may say that the idea of time is bound up with the idea of causation and functional interdependence. Without time, causation cannot exist, just as without time, motion or the absence of motion cannot exist. But our perception concerning our "being in time" is entangled and misty up to improbability. First of all let us analyze our relation toward the past, present and future. Usually we think that the past already does not exist . It has passed, disappeared, altered, transformed itself into something else.