arked as in the physical, and the
actions and reactions of the mind of man have not yet proved to be
susceptible of reduction to exact formulae. Nevertheless, man, in his
intuitive search for valid guides for his own action, has been able,
with the advance of time, greatly to improve his own lot through the
medium of the scientific approach to human problems.

The insistent search of the human mind for reliable rules of action is
a recognized natural phenomenon. As understood on the basis of expert
investigation of the subject, this trait results from the recognition,
conscious or otherwise, by countless generations of mankind, of the
relationships between cause and effect as evidenced in the workings of
the laws of nature (page 22). A logical outcome, therefore, of
experience, this instinctive demand of the mind constitutes a force
which defies opposition. Properly utilized, this force affords a
powerful and natural aid in the solution of problems.

Inasmuch as a valid rule, or principle, is of great assistance in
arriving at sound decisions and in formulating effective plans (see
page 22), this demand for reliable guides is logical, as well as
natural. In any event, the demand for such guidance, if not met by
provision for reliable rules of action, may result in the adoption of
faulty rules, with frequent unfortunate consequences.

The formulation of principles, already referred to in this connection,
constitutes in itself a recognized problem (see also page 27) of great
difficulty; for it is a human failing to avoid the mental effort
involved in thinking through such a problem, and to rely on rules
whose plausibility and seeming simplicity are frequently a measure of
their incompleteness and inaccuracy.

Since the earliest days, man has attempted to formulate the
relationships between causes and effects without, however, always
possessing the specific knowledge essential to accuracy. Pithy
statements have always had great appeal to man, as evidenced by the
existence of proverbs, maxims, and adages preserved from times of
great antiquity. Frequently, however, such statements are not
expressive of the truth. Sometimes, again, they state facts, without,
nevertheless, expressing the whole truth.

Only when the relationship between cause and effect has been
demonstrated to be always true can the trained, inquiring mind receive
its statement as a valid guide, acceptable as a principle in the light
of the knowledge of