aware. Memory links night to night and
winter to winter, but such things as "the night-time of the spirit"
and "the winter of our discontent" are not recognized as having either
cause or consequence. Now though the well-springs of these states of
consciousness remain obscure, there is nothing unreasonable in
believing that they are recrudescences of far-off, forgotten moods
and moments; neither is it absurd to suppose that they may be related
to the movements and positions of the planets, as night and winter
are related to the axial and orbital movements of the earth.

But there are other, and even more interesting, evidences of time
curvature in consciousness. These lead away into new regions which
it is our pleasure now to explore.

VI SLEEP AND DREAMS

SLEEP

Our space is called three-dimensional because it takes three
numbers--measurement in three mutually perpendicular directions--to
determine and mark out any particular point from the totality of
points. Time, as the individual experiences it, is called
one-dimensional for an analogous reason: one number is all that is
required to determine and mark out any particular event of a series
from all the rest. Now in order to establish a position in a space of
four dimensions it would be necessary to measure in _four_ mutually
perpendicular directions. Time curvature opens up the possibility of
a corresponding higher development in time: one whereby time would
be more fittingly symbolized by a plane than by a linear figure.
Indeed, the familiar mystery of memory calls for such a conception.
Memory is a carrying forward of the past into the present, and the
fact that we can recall a past event without mentally rehearsing
all the intermediate happenings in inverse order, shows that in
the time aspect of memory there is simultaneity as well as
sequence--time ceases to be linear and becomes _plane_. More
remarkable illustrations of the sublimation of the time-sense are
to be found in the phenomena of sleep and dreams.

"Oh, thou that sleepest, what is sleep?" asks the curious Leonardo.
Modern psychological science has little to offer of a positive
nature in answer to this world-old question, but it has at least
effectively disposed of the absurd theories of the materialists who
would have us believe that sleep is a mere matter of blood
circulation or of intoxication by accumulation of waste products in
the system. Sleep states are not abnormal, but part and