2. Having perceived a great number of things as extended, with the intervals of un occupied extension that separate these, we form an idea of extension in the abstract. The distinguishing peculiarity of this abstraction is related to unoccupied extension, or empty space, where we seem to have extension without anything extended; rendering the idea of space unlike other abstract ideas, as gravity, or justice, which are conceiv able only as embodied in gravitating things, or just actions. Still, empty space is a real ity to us, inasmuch as it expresses cessation of resistance, and free scope for movement. To the senses alone, without the muscular accompaniments, space would be a nonentity: an inconceivability; hut the feeling of the sweep of the arm, or of the locomotion of the body, in passing from one point of resistance to another is a genuine mental experience —the tilling up of the interval between two tactile encounters, or between two optical pictures, with conscious activity.
The idea of TIME, continuance, or endurance, applies both to our feelings of energy put forth, and also to our sensations, emotions, and the flow of our ideas; in other words, it attaches both to the extended or object world, and to the unextended or sub ject mind. In our muscular feelings, which represent the universe of matter and space,
we discriminate a dead strain, or effort of resistance, lasting a short time from the same strain lasting a longer time; and also a more persisting movement from a lets. - So in the sensations; a sound enduring a second is different to us from a sound two seconds: a transitory odor is not confOunded with one of greater continuance. We dis tinguish two bursts of wonder, terror, love, or anger, if they have been unequal in tsieir duration. Abstracting from all these experiences of continuance in the concrete. we ob tain the idea of time; which idea, however, like other abstractions, must be conceived by us under sonic individual continuing thing. If we were to imagine the whole outward universe annihilated, we should still have, in our own consciousness, an instance of the continuing, and upon that we could sustain the conception of time. See GENERALIZA TION.
Time is measured by space, and space by time. The one is often expressed by the other, but with a certain limitation; we say "a space of time," hut not " a time of space." Movement is common to both. Of passive sensations, the best for indicating time are those of hearing