ble that our sense of the few seconds of passing time that
we call the _immediate present_ consists of the recognition of the
succession of these pulsations of consciousness, together with certain
organic rhythms, such as heart beat and breathing.

NO PERCEPTION OF EMPTY TIME.--Our perception does not therefore act upon
empty time. Time must be filled with a procession of events, whether
these be within our own consciousness or in the objective world without.
All longer periods of time, such as hours, days, or years, are measured
by the events which they contain. Time filled with happenings that
interest and attract us seems short while passing, but longer when
looked back upon. On the other hand, time relatively empty of
interesting experience hangs heavy on our hands in passing, but, viewed
in retrospect, seems short. A fortnight of travel passes more quickly
than a fortnight of illness, but yields many more events for the memory
to review as the "filling" for time.

Probably no one has any very accurate feeling of the length, that is,
the actual _duration_ of a year--or even of a month! We therefore divide
time into convenient units, as weeks, months, years and centuries. This
allows us to think of time in mathematical terms where immediate
perception fails in its grasp.

5. THE TRAINING OF PERCEPTION

In the physical world as in the spiritual there are many people who,
"having eyes, see not and ears, hear not." For the ability to perceive
accurately and richly in the world of physical objects depends not alone
on good sense organs, but also on _interest_ and the habit of
_observation_. It is easy if we are indifferent or untrained to look at
a beautiful landscape, a picture or a cathedral without _seeing_ it; it
is easy if we lack interest or skill to listen to an orchestra or the
myriad sounds of nature without _hearing_ them.

PERCEPTION NEEDS TO BE TRAINED.--Training in perception does not depend
entirely on the work of the school. For the world about us exerts a
constant appeal to our senses. A thousand sights, sounds, contacts,
tastes, smells or other sensations, hourly throng in upon us, and the
appeal is irresistible. We must in some degree attend. We must observe.

Yet it cannot be denied that most of us are relatively unskilled in
perception; we do not know how, or take the trouble to observe. For
example, a stranger was brought into the classroom and introduced by the
instructor to a class of fifty