J.—PSYCHOLOGY 173 
EMPIRICAL AND EXacT SCIENCES. 
In the same way as the sciences of Nature, concerning themselves with 
sensed-things, make a selection from among our experiences, omit many, 
and abstract from the fact that they are experiences of ours, so other 
sciences, concerning themselves with thought-things, make another 
selection of experiences, and consider them as if they also were independent 
of us. The empirical sciences that begin with sensory material work 
from this towards its explanation on conceptual lines. ‘Those sciences 
like mathematics, on the other hand, that begin with abstract quantitative 
concepts, work from these concepts and their relations towards a state- 
ment of the implications that are contained within them. The former 
sciences derive the force of conviction with which they impress us from 
the fact that they are ultimately based upon the evidence of our senses— 
‘Seeing is believing.’ The latter likewise convince us by their proofs, 
because their conclusions evidently follow from their premisses— There 
is no proof like a mathematical proof.’ The point to be stressed again, 
however, is that both these kinds of science are selective of their material 
and leave out of account much experience which, as such, is as good as any 
other. If seeing is believing, and mathematical proof convincing, the 
immediate living experience of myself knowing and feeling and willing is 
most impressive of all. Though not a Cartesian, in this I agree with 
Descartes that such experience is not merely believable or convincing, 
but indubitable. I suggest that these neglected experiences are necessary 
to explain the constructions of the empirical sciences of Nature, for we 
need no longer concern ourselves with the deductive sciences. And 
I further suggest that it is psychology, concerned with the totality of 
experience, objective and subjective alike, of which we are or may be 
conscious, and making no abstraction from the fact that it 7s experience, 
which provides an account of the empirical origin of principles of systema- 
tisation and explanatory concepts alike which are used in the other sciences. 
Though these principles and concepts are abstract, and indeed vary in 
degrees of abstraction, from qualities and their relations, through quan- 
tities and their relations, to being and its relations, in a sort of hierarchical 
order, they are and must be abstracted from something ; and if that 
something is not the sensory material with which physical science deals, 
then it must be discovered in some other region of experience. To 
support this contention it is not necessary to have recourse to innate 
ideas ; for it can be shown that observable mental processes, other than 
the apprehension of sensory experience, can account for the facts. And 
these processes are the apprehension and abstraction of relations between 
any experiences, this term being taken in the broadest sense, the pro- 
duction of correlates in respect of any experience, and the immediate 
awareness of the self energising, or being in one way or another busy 
with its objects. I summarise these considerations as follows. All 
systematic principles and explanatory concepts are in some way derived 
from experience. They are all mental products, the results of mental 
processes. They differ in degree of abstraction. Psychology is concerned 
with the totality of experience as such, and the processes, among others, 
