en two
extreme points at which it ceases to exist: viz., perfect unity and
absolute inco-ordination. All the intermediate degrees are met with, in
fact, and without any line of demarcation between the healthy and the
morbid; the one encroaches upon the other.

Even in the normal state the co-ordination is often sufficiently loose
to allow several series to coexist separately. We can walk or perform
manual work with a vague and intermittent consciousness of the
movements, at the same time singing, musing; but if the activity of
thought increases, the singing will cease. With many people it is a kind
of substitute for intellectual activity, an intermediate state between
thinking and not-thinking.

The unity of the ego, in a psychological sense, is, therefore, the
cohesion, during a given time, of a certain number of clear states of
consciousness, accompanied by others less clear, and by a multitude of
physiological states which, without being accompanied by consciousness
like the others, yet operate as much as, and even more than, the former.
Unity, in fact, means co-ordination. The conclusion to be drawn from the
above remarks is namely this, that the consensus of consciousness being
subordinate to the consensus of the organism, the problem of the unity
of the ego is, in its ultimate form, a biological problem. To biology
pertains the task of explaining, if it can, the genesis of organisms and
the solidarity of their component parts. Psychological interpretation
can only follow in its wake.

2. Personality as a Complex[70]

Ideas, after being experienced in consciousness, become dormant
(conserved as physiological dispositions) and may or may not afterward
be reawakened in consciousness as memories. Many such ideas, under
conditions with some of which we are all familiar, tend to form part of
our voluntary or involuntary memories and many do not. But when such is
the case, the memories do not ordinarily include the whole of a given
mental experience, but only excerpts or abstracts of it. Hence one
reason for the fallibility of human memory and consequent testimony.

Now under special conditions, the ideas making up an experience at any
given moment tend to become organized into a system or complex, so that
when we later think of the experience or recall any of the ideas
belonging to it, the complex as a whole is revived. This is one of the
principles underlying the mechanism of memory. Thus it happens that
memory