tnote 2: _Ibid._, p. 329.]

[Footnote 1: James gives an illuminating passage on the importance
of the effectiveness of _reasoning_ things out: "I have a
student's lamp, of which the flame vibrates most unpleasantly unless
the collar which bears the chimney be raised about a sixteenth of
an inch. I learned the remedy after much torment by accident, and
now always keep the collar up with a small wedge. But my procedure
is a mere association of two totals, diseased object and remedy.
One learned in pneumatics could have named the _cause_ of the
disease, and thence inferred the remedy immediately. By many
measurements of triangles, one might find their area always equal
to their height multiplied by half their base, and one might
formulate an empirical law to that effect. But a reasoner saves himself
all this trouble, by seeing that it is the essence (_pro hac vice_)
of a triangle to be the half of a parallelogram whose area is the height
into the entire base. To see this he must invent additional lines; and
the geometer must often draw such to get at the essential properties
he may require in a figure. The essence consists in some _relation
of the figure to the new lines_, a relation not obvious at all until
they are put in. The geometer's sagacity lies in the invention of the
new lines." (_Psychology_, vol. II, pp. 339-40.)]

But no thinking is conclusive until after the experimental
certification and warranting of the idea which has been held
in mind as the solution of the problem. By deduction, by
logical elaboration of an idea, we find its adoption involves
certain consequences. Some of the logical consequences
which follow from an idea may indicate that it is a plausible
solution of our problem. But no matter how plausible a
suggestion looks, until it is verified by observation or experiment
the thinking process is not concluded, is not finished,
as we say, _conclusively_. When an idea or a suggestion has
been developed, and seen to involve--as an idea--certain
inevitable logical consequences, the idea must be tested by
further observation and experiment. Suggestions arise _from_
facts and must be tested _by_ them. Until the suggestion is
verified, it remains merely a suggestion, a theory, a hypothesis,
an idea. It is only when the consequences implied logically
in the very idea itself are found in the actual situation
that the idea is accepted as a solution to the problem. Sometimes
the suggestion may be verified