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190 been seen ceases thereupon to exist, that what is not seen yet will spring to life all in a moment. In other words, your space-sense, thus reduced or narrowed, takes on those attributes which we are accustomed to associate with time.

This illustrates how the time-sense may be an imperfect sense of higher space, the movement of consciousness on a dimension not otherwise known, not otherwise sensed, foreign to experience. What appear to us as phenomena—changes proceeding in the things of our world—may be but the involvement in our space of a dimension of which weare not spatially aware. Life, growth, organic being, the transition from simplicity to complexity, the shrinkage and expansion of solids—all these, to this view, are evidences of a four-dimensional extension, because they involve relations which cannot be expressed in terms of length, breadth, and height, but require also time.

It will be helpful in understanding how this may be so by dramatizing the predicament of a consciousness limited to the two dimensions of a plane—a flatman—in trying to understand the nature of a solid of our space passing through that plane which constitutes his world. The third dimension of such a solid (the one perpendicular to his plane) would not manifest itself to him as spatial extension, but as temporal change, as a principle of growth, and as a measure of relations incapable of being expressed in terms of length and width merely—the only two dimensions that he knows. All he would be conscious of would be the changing cross-section which the solid traced, defined by the displacement of the constituent matter of his plane. This would seem to him to be matter in a dynamic condition. His watch would be his only tape-measure for the third dimension. Imagine, for example, a cone, passed apex downward through the plane. It would appear there first as a point, expanding into a circle, and this still expanding circle would suddenly disappear. These modifications would be caused by the gradual involvement of the third—the vertical—dimension of the cone in the two dimensions of the plane. They would be the time expression of the cone's extension in the third dimension, and no other expression would be comprehensible to the flatman. In the same way, the fourth dimension—as spatial extension—is not otherwise comprehensible to us.

These new concepts of space and time bid fair to produce a revo-