lid reason they afford for believing in the existence of still
deeper strata of mental operations, sunk wholly below the level of
consciousness, which may account for such mental phenomena as cannot
otherwise be explained. We gain an insight by these experiments into
the marvellous number and nimbleness of our mental associations, and
we also learn that they are very far indeed from being infinite in
their variety. We find that our working stock of ideas is narrowly
limited and that the mind continually recurs to the same instruments
in conducting its operations, therefore its tracks necessarily
become more defined and its flexibility diminished as age advances.

ANTECHAMBER OF CONSCIOUSNESS.

When I am engaged in trying to think anything out, the process of
doing so appears to me to be this: The ideas that lie at any moment
within my full consciousness seem to attract of their own accord the
most appropriate out of a number of other ideas that are lying close
at hand, but imperfectly within the range of my consciousness. There
seems to be a presence-chamber in my mind where full consciousness
holds court, and where two or three ideas are at the same time in
audience, and an antechamber full of more or less allied ideas,
which is situated just beyond the full ken of consciousness. Out of
this antechamber the ideas most nearly allied to those in the
presence-chamber appear to be summoned in a mechanically logical way,
and to have their turn of audience.

The successful progress of thought appears to depend--first, on a
large attendance in the antechamber; secondly, on the presence there
of no ideas except such as are strictly germane to the topic under
consideration; thirdly, on the justness of the logical mechanism
that issues the summons. The thronging of the antechamber is, I am
convinced, altogether beyond my control; if the ideas do not appear,
I cannot create them, nor compel them to come. The exclusion of
alien ideas is accompanied by a sense of mental effort and volition
whenever the topic under consideration is unattractive, otherwise it
proceeds automatically, for if an intruding idea finds nothing to
cling to, it is unable to hold its place in the antechamber, and
slides back again. An animal absorbed in a favourite occupation
shows no sign of painful effort of attention; on the contrary, he
resents interruption that solicits his attention elsewhere. The
consequence of all this is that the mind freque