ith the definition of perception. We there
decided that those particulars which constitute the physical world can
be collected into sets in two ways, one of which makes a bundle of all
those particulars that are appearances of a given thing from different
places, while the other makes a bundle of all those particulars which
are appearances of different things from a given place. A bundle of
this latter sort, at a given time, is called a "perspective"; taken
throughout a period of time, it is called a "biography." Subjectivity is
the characteristic of perspectives and biographies, the characteristic
of giving the view of the world from a certain place. We saw in Lecture
VII that this characteristic involves none of the other characteristics
that are commonly associated with mental phenomena, such as
consciousness, experience and memory. We found in fact that it is
exhibited by a photographic plate, and, strictly speaking, by any
particular taken in conjunction with those which have the same "passive"
place in the sense defined in Lecture VII. The particulars forming one
perspective are connected together primarily by simultaneity;
those forming one biography, primarily by the existence of direct
time-relations between them. To these are to be added relations
derivable from the laws of perspective. In all this we are clearly not
in the region of psychology, as commonly understood; yet we are also
hardly in the region of physics. And the definition of perspectives
and biographies, though it does not yet yield anything that would
be commonly called "mental," is presupposed in mental phenomena, for
example in mnemic causation: the causal unit in mnemic causation, which
gives rise to Semon's engram, is the whole of one perspective--not of
any perspective, but of a perspective in a place where there is nervous
tissue, or at any rate living tissue of some sort. Perception also,
as we saw, can only be defined in terms of perspectives. Thus the
conception of subjectivity, i.e. of the "passive" place of a particular,
though not alone sufficient to define mind, is clearly an essential
element in the definition.

I have maintained throughout these lectures that the data of psychology
do not differ in, their intrinsic character from the data of physics.
I have maintained that sensations are data for psychology and
physics equally, while images, which may be in some sense exclusively
psychological data, can only be distinguished from