in himself of any one elementary faculty.  This concentrated type of attention is an elementary faculty:  it is one of the things that might be ascertained and measured by exercises in the laboratory.  But, having ascertained it in a number of persons, we could never rank them in a scale of actual and practical mental efficiency based on its degrees.  The total mental efficiency of a man is the resultant of the working together of all his faculties.  He is too complex a being for any one of them to have the casting vote.  If any one of them do have the casting vote, it is more likely to be the strength of his desire and passion, the strength of the interest he takes in what is proposed.  Concentration, memory, reasoning power, inventiveness, excellence of the senses,—­all are subsidiary to this.  No matter how scatter-brained the type of a man’s successive fields of consciousness may be, if he really care for a subject, he will return to it incessantly from his incessant wanderings, and first and last do more with it, and get more results from it, than another person whose attention may be more continuous during a given interval, but whose passion for the subject is of a more languid and less permanent sort.  Some of the most efficient workers I know are of the ultra-scatterbrained type.  One friend, who does a prodigious quantity of work, has in fact confessed to me that, if he wants to get ideas on any subject, he sits down to work at something else, his best results coming through his mind-wanderings.  This is perhaps an epigrammatic exaggeration on his part; but I seriously think that no one of us need be too much distressed at his own shortcomings in this regard.  Our mind may enjoy but little comfort, may be restless and feel confused; but it may be extremely efficient all the same.

XII.  MEMORY

We are following a somewhat arbitrary order.  Since each and every faculty we possess is either in whole or in part a resultant of the play of our associations, it would have been as natural, after treating of association, to treat of memory as to treat of interest and attention next.  But, since we did take the latter operations first, we must take memory now without farther delay; for the phenomena of memory are among the simplest and most immediate consequences of the fact that our mind is essentially an associating machine.  There is no more pre-eminent example for exhibiting the fertility of the laws of association as principles of psychological analysis.  Memory, moreover, is so important a faculty in the schoolroom that you are probably waiting with some eagerness to know what psychology has to say about it for your help.