We have been thus full and express on this subject, because these simple ideas of time, space, and motion, of length, breadth, and depth, are not only the simplest and universal, but the necessary symbols of all philosophic construction. They will be found the primary factors and elementary forms of every calculus and of every diagram in the algebra and geometry of a scientific physiology. Accordingly, we shall recognise the same forms under other names; but at each return more specific and intense; and the whole process repeated with ascending gradations of reality, _exempli gratiâ_: Time + space = motion; T_m_ + space = line + breadth = depth; depth + motion = force; L_f_ + B_f_ = D_f_; LD_f_ + BD_f_ = attraction + repulsion = gravitation; and so on, even till they pass into outward phenomena, and form the intermediate link between productive powers and fixed products in light, heat, and electricity. If we pass to the construction of matter, we find it as the product, or _tertium aliud_, of antagonist powers of repulsion and attraction. Remove these powers, and the conception of matter vanishes into space—conceive repulsion only, and you have the same result. For infinite repulsion, uncounteracted and alone, is tantamount to infinite, dimensionless diffusion, and this again to infinite weakness; viz., to space. Conceive attraction alone, and as an infinite contraction, its product amounts to the absolute point, viz., to time. Conceive the synthesis of both, and you have matter as a fluxional antecedent, which, in the very act of formation, passes into body by its gravity, and yet in all bodies it still remains as their mass, which, being exclusively calculable under the law of gravitation, gives rise, as we before observed, to the science of statics, most improperly called celestial mechanics. In strict consistence with the same philosophy which, instead of considering the powers of bodies to have been miraculously stuck into a prepared and pre-existing matter, as pins into a pin-cushion, conceives the powers as the productive factors, and the body or phenomenon as the fact, product, or fixture; we revert again to potentiated length in the power of magnetism; to surface in the power of electricity; and to the synthesis of both, or potentiated depth, in constructive, that is, chemical affinity. But while the two factors are as poles to each other, each factor has likewise its own poles, and thus in the simple cross—