in the next instant, through the action of new "moments" of force, the greatest resistance. Any direction as well as any change of direction implies, then, resistance; resistance is equivalent to the interference of force, or, in other words, to competition; and competition may, at any moment, become catastrophe. The difference between competition and catastrophe is one merely of degree, or rather it is a subjective difference depending upon the point of view of the observer. In other words, all that we can testify to is a certain periodicity of motion, all motion meeting with resistance, the accumulation of which finally induces motion in another sense. Larger periodicities are made up of smaller periodicities, and, according to the point of view taken, any period of such motion may be regarded as an evolution, that which Fechner terms "full" stability being only the maximum towards which motion during that period tends. Absolute stability can be conceived only as perfect rest, whether we conceive it as merely an abstraction, its realization as rendered impossible by the conservation of energy, or whether we conceive it as possible in a universe regarded as finite; an absolute stability of motion is a self-contradiction, and a full stability which knows no retrogression is equally a self-contradiction. Periodicity is, then, all into which the Tendency to Stability resolves itself for nature as we know it. We perceive, in the actual universe, the fact of a certain imperfect periodicity. This wave form of movement in great and little plays, as Spencer has shown far more elaborately than Fechner, a large part in the universe.