by observation; sometimes
conditions must be deliberately arranged for testing its
adequacy. In either case it is only when the facts of the
situation correspond to the conditions theoretically involved that
the tentative idea is accepted as a conclusion.

Thus a treatment that is regarded by the doctor as a possible
cure can be called an actual cure only when its beneficent
results are observed. The supposition about the planet
Neptune is only verified when the planet is actually observed
in the heavens. Thinking ends, as it begins, in observation.
At the beginning the facts are carefully examined to see
precisely where the difficulty lies; at the end they are again
examined to see whether an idea, an entertained hypothesis,
a suggested solution, can be verified in actual observable
results.

THE QUALITY OF THINKING--SUGGESTION. The quality of thinking
varies, first, with the fertility of suggestion of the analyzing
mind. Ease of suggestion, in the first place, depends on innate
individual differences. There are some minds so constituted
that every fact provokes a multitude of suggestions.
Readiness in responding with "ideas" to any experience is
dependent primarily on initial differences in resilience and
responsiveness. But differences in training and past experience
are also contributory. A man who has much experience
in a given field, say in automobile repairing, will, given a
difficulty, not only think of more suggestions, but think more
rapidly in that field.

Again persons differ in range or number of suggestions that
occur. The quality of the thinking process and of the results
it produces depends, in part, on the variety of suggestions which
occur to an individual in the solution of a given problem. If
too few suggestions occur one may fail to hit upon any promising
solution. If too many suggestions occur one may be
too confused to arrive at any conclusion at all. Whether an
individual has few or many suggestions depends largely on
native differences. It depends, also, however in part, on
acquaintance with a given field. And the fertility of suggestions
may be increased by a careful survey and re-survey of
the facts at hand, and by the deliberate searching-out of
further facts from which further suggestions may be derived.
Suggestions differ, finally, in regard to depth or significance;
by nature and by training, individuals produce ideas of varying
degrees of significance in the solution of problems.