TO some people the very idea of measuring personality seems faintly sacrilegious, and they are inclined to deny its possibility along with its desirability. The many able psychologists who have been flung back, baffled and dismayed, in their attempts to obtain valid measurements, know, however, that the secret is unlikely to be revealed to anyone without a degree of enlightenment which would make unwise and irreverent use improbable. Certainly the problems to be faced are extremely subtle ones and only the fact that we at present stand merely on the fringe of their complexity justifies an attempt to deal with the subject in a work of this size.