186 SECTIONAL ADDRESSES. 
because measurement is excluded; the truth being that, even where 
measurement is excluded, the possibilities of systematic observation and 
experiment still remain. Natural science has surely a function wider than 
that of merely reducing its subject-matter to units of space and time. 
Highly valuable and deserving of the utmost encouragement as is the 
measurement of behaviouristic data, however helpful be the light they 
may ultimately throw on mental processes and their general characters, 
however wider be mental processes than the range of mere conscious 
experience, the scientific study of the mind by direct observation and 
experiment is never to be discountenanced or discarded. 
SELF-ACTIVITY. 
Just as experimental physics patiently pursues its researches into 
Nature, heedless of such mathematical conclusions as are not amenable 
to verification by experiment—so experimental psychology must realise 
that its progress is not primarily dependent on, however much assistance 
it may receive from, the work of those who fail to recognise that the 
fundamental subject-matter of psychology is conscious experience, not 
conduct. Now conscious experience can only be enjoyed by the active 
self, i.e. the ‘individual’ (i.e. undivided) mental activity of the entire 
living organism. It is the fundamental function of such self-activity—by 
recourse to past experiences, by receiving present experiences, by fore- 
seeing future experiences and by creating new experiences—to select from 
alternative responses and from alternative environments those which are 
most advantageous to the ever evolving and developing organism. To 
secure the most suitable movements and environment and thus to help in 
the evolution of the organism are the prime objects of consciousness ; 
and where, as in plants, mobility and plasticity are at a minimum, sellf- 
activity and consciousness are inappreciable. Self-activity is to be 
regarded as the highest, unitary imtegration of the directive mental 
(conscious and unconscious) activity of the organism. 
THE DERIVATION OF PRESENTATIONS (OR CONTENTS) FROM FEELINGS. 
Self-activity and its inherent consciousness may presumably be traced 
back to a stage where self and not-self are but just distinguishable. At 
this remote stage in animal evolution there can hardly have been more 
than a differentiation of self-activity into ‘ acts’ of the self and ‘ modifica- 
tions’ of the self. These modifications of the self became early 
itn colts het 
differentiated into (a) those which are due to internal happenings within — 
the organism, and (b) those which are due to more variable external — 
happenings in its environment, and later into (a) those which we come to 
recognise as ‘ affects’ of the self and ‘ feeling tones’ and (6) those which 
come to be regarded as * presentations ’ to the self or as “ contents’ of the 
self’s consciousness. Sensations, perceptions, memories and thoughts— 
all that we finally come to recognise as conscious presentations to the 
selfi—have been differentiated (onto- and phylo-genetically) from modifica- 
tions of the self: instead of being feelings of the self, they have become 
contents of consciousness. 
