understood without the other. Every thought reverberates through the
body, and, on the other hand, alterations in our physical condition
affect our whole attitude of mind. The insufficient elimination of the
foul and decaying products of digestion may plunge us into deep
melancholy, whereas a few whiffs of nitrous monoxide may exalt us to
the seventh heaven of supernal knowledge and godlike complacency. And
vice versa, a sudden word or thought may cause our heart to jump,
check our breathing, or make our knees as water. There is a whole new
literature growing up which studies the effects of our bodily
secretions and our muscular tensions and their relation to our
emotions and our thinking.

Then there are hidden impulses and desires and secret longings of
which we can only with the greatest difficulty take account. They
influence our conscious thought in the most bewildering fashion. Many
of these unconscious influences appear to originate in our very early
years. The older philosophers seem to have forgotten that even they
were infants and children at their most impressionable age and never
could by any possibility get over it.

The term "unconscious", now so familiar to all readers of modern works
on psychology, gives offense to some adherents of the past. There
should, however, be no special mystery about it. It is not a new
animistic abstraction, but simply a collective word to include all the
physiological changes which escape our notice, all the forgotten
experiences and impressions of the past which continue to influence
our desires and reflections and conduct, even if we cannot remember
them. What we can remember at any time is indeed an infinitesimal part
of what has happened to us. We could not remember anything unless we
forgot almost everything. As Bergson says, the brain is the organ of