J.—PSYCHOLOGY - 217 
But his most fruitful contribution lay in the development of two tech- 
nical methods of inquiry, the statistical method of correlation, and the 
experimental method of psychological tests. These in turn rest upon a 
fundamental assumption, which recent work has verified—the con- 
tinuity of mental variation. Here stands the keystone of individual 
psychology as a science. The differences between one man and another 
are always (we shall find) a matter of ‘ more or less ’—seldom, if ever, 
a question of presence or absence, of ‘ all or none.’ 
‘ Virtuous and vicious ev’ry man must be, 
Few in th’ extreme, but all in a degree.’ ° 
There are, in fact, no such things as mental types ; there are only mental 
tendencies. And it becomes the main task of individual psychology, 
first, to catalogue and classify all the tendencies to be surveyed, and then 
to devise a method for the quantitative assessment of each. 
It follows from this initial postulate that the mind of every individual 
has the same underlying structure. Men’s minds are like their faces. 
Hach seems at first unique. But patient analysis shows that the 
real component features are in every one the same. All have two eyes, 
two ears, a mouth, a forehead, and a nose. But the length, the width, 
and the prominence of each part may differ infinitely from man to man. 
Our business is thus to calculate the extent to which each known 
potentiality has been developed or contracted, much as a surveyor marks 
down, at given stations upon his map, the eminences and depressions 
of the land. 
The Psychographic Scheme. 
Since the mental ground-plan is in all persons approximately the 
same, the same inventory of mental tendencies will serve, no matter 
which particular person we are about to analyse. An identical set 
of questions may be asked about each.. An identical series of headings 
will recur in our reports. Were our psychological catalogue exhaustive 
and complete, it would, in theory, be necessary only to measure in 
Succession each particular capacity; and so obtain a clear and quanti- 
tative specification of the idiosyncrasy of each individual. 
This view is more than a mere dogmatic postulate. It is confirmed 
by a close comparison of the literature in different psychological fields. 
li will be discovered that, whatever the nature of the case to be ex- 
amined—mental deficiency or supernormal talent, educational back- 
wardness or vocational misfit, neurotic disorder or propensity to crime 
—practical experience has forced each examining psychologist to work 
out very much the same main heads of inquiry as his colleagues in 
other lines. Such a working schedule of mental characteristics may 
be termed a ‘ psychographic scheme.’ The scheme that I shall follow 
here will be one which I have found reappearing as a basis for my 
note-taking in investigating individuals in each of the foregoing groups. 
In its broadest outlines every personal examination should pursue 
two chief directions: first, a retrospective inquiry into the past history 
of the person studied; and, secondly, what I may call a conspective 
5 Pope, Hssay on Man, 231. 
