We must not forget, however, that the process of buying deserves the same psychological interest as that of selling.  If psychotechnics is to be put into the service of a valuable economic task, the goal cannot possibly be to devise schemes by which the customer may easily be trapped.  The purpose of science cannot be to help any one to sell articles to a man who does not need them and who would regret the purchase after quiet thought.  The applied psychologist should help the prospective buyer no less, and must protect him so that his true intention may become realized in the economic process.  Otherwise through his suggestibility, the determining idea of his goal might fade in his consciousness and the appeal to his vanity or to his instincts might awaken an anti-economic desire which he would be too weak to inhibit.  The salesman must know how to use arguments and suggestions and how to make them effective,[55] but the customer too must know how to see through a misleading argument and how to resist mere suggestion.

The postulate that the psychical factors in commercial life are to be carefully regarded is repeated in more complex form in the wholesale business and in the stock exchange.  It is a perfectly justified and consistent thought which recently led a large credit bureau to an effort to base its information on psychological analysis.  It is well known that there are bureaus in which the ledger experiences of a large circle of companies in the same commercial line are collected, tabulated, and recorded, thus affording an automatic review of the occurrences, focusing early attention on doubtful accounts and pointing out weaknesses in the customers’ conditions, as they develop, as well as evidences of prosperity.  The ledger experience which a single company has with all its customers is tabulated without revealing its identity to the associates, who get reports containing it, and the many combined ledgers become a valuable guide.  Yet all such methods can show only actual movements in the market, and cannot allow the prospects of future development to be determined, simply because they cannot take into account the personal equations.  Only an acquaintance with the character and the temperament, the intelligence and the habits, the energy and the weakness, of the head of a firm can tell us whether the company, even with satisfactory resources, may go down, or whether, even though embarrassed, it may hold out.  The psychological pioneer, therefore, aims not only toward an exchange of ledger accounts, but toward a real psychological diagnosis and prognosis.  If a member of a firm is personally known to some scores of business men who have had commercial dealings with him, and each one of them, without disclosing his identity to any one but the central bureau, sends to it a statement of personal impressions, a composite picture of the mental physiognomy can be worked out.  Of course all this has been often done in the terms of popular psychology and in a haphazard, amateurish way.  The new plan is to arrange the questions systematically under the point of view of scientific descriptive psychology.  Regular psychograms, in which the probability of a particular kind of behavior is to be determined in an exact percentage calculation, are to replace the traditional vagueness, as soon as a sufficient number of reliable answers have been tabulated.