While we
wake and while we sleep, while we are unconscious under an anaesthetic,
even, some sort of mental process continues. Sometimes the stream flows
slowly, and our thoughts lag--we "feel slow"; again the stream flows
faster, and we are lively and our thoughts come with a rush; or a fever
seizes us and delirium comes on; then the stream runs wildly onward,
defying our control, and a mad jargon of thoughts takes the place of our
usual orderly array. In different persons, also, the mental stream moves
at different rates, some minds being naturally slow-moving and some
naturally quick in their operations.

Consciousness resembles a stream also in other particulars. A stream is
an unbroken whole from its source to its mouth, and an observer
stationed at one point cannot see all of it at once. He sees but the one
little section which happens to be passing his station point at the
time. The current may look much the same from moment to moment, but the
component particles which constitute the stream are constantly changing.
So it is with our thought. Its stream is continuous from birth till
death, but we cannot see any considerable portion of it at one time.
When we turn about quickly and look in upon our minds, we see but the
little present moment. That of a few seconds ago is gone and will never
return. The thought which occupied us a moment since can no more be
recalled, just as it was, than can the particles composing a stream be
re-collected and made to pass a given point in its course in precisely
the same order and relation to one another as before. This means, then,
that we can never have precisely the same mental state twice; that the
thought of the moment cannot have the same associates that it had the
first time; that the thought of this moment will never be ours again;
that all we can know of our minds at any one time is the part of the
process present in consciousness at that moment.

[Illustration: FIG. 1]

[Illustration: FIG. 2]

THE WAVE IN THE STREAM OF CONSCIOUSNESS.--The surface of our mental
stream is not level, but is broken by a wave which stands above the
rest; which is but another way of saying that some one thing is always
more prominent in our thought than the rest. Only when we are in a
sleepy reverie, or not thinking about much of anything, does the stream
approximate a level. At all other times some one object occupies the
highest point in our thought, to the more or less complete exclusio