Turn now to the =psychology of the abnormal mind=. Here we find, under the heading of _individual_ psychology, (8) the psychology of _deficient and exceptional minds_; of blind deaf-mutism, of genius, of the subnormal and the supernormal child; (9) the psychology of _temporary mental derangement_; of dream, of hypnosis, of intoxications, of occasional hallucination and illusion; and (10) the psychology of _permanent mental disorder_, of the chronic derangements of insanity. We may also study (11) the psychology of _temporary derangement_ of the _collective_ mind, that is, of the manias or mental epidemics that sometimes sweep society: the mediæval dance-manias, unmotived panics, outbursts of superstition, of religious persecution. If we proceed further, from psychology proper to =psychotechnics=, or to what is ordinarily termed applied psychology, we have the great departments of (12) _educational_ psychology, (13) _medical_ psychology or psychotherapeutics, (14) _juristic_ psychology, or the psychology of evidence and testimony, and (15) _economic_ psychology, which includes such things as vocational psychology and the psychology of advertising. You need not ascribe any special importance to this classification; still less need you memorise it. The various topics might very likely be better arranged, and the list is by no means complete. Realise, however, that every term in the list has its text-books and treatises, its manuals and monographs, and very likely its magazine or magazines; realise again that, although the emphasis varies in the different countries, the list might be filled out not alone in English, but in all the chief European tongues; and remember, lastly, that some of the headings have a very long history, and a correspondingly long series of printed works over and above those that represent current knowledge. You then get a glimmering of =the range and scope of psychology=. It is true, of course, that much of what has been printed is out of date, or inaccurate, or superficial, or prejudiced, and for these or like reasons may safely be scrapped. Yet it all has to be sifted.