they can be brought to the domain of the present in order to be able to
associate the former phenomena with those from which it is a question of
drawing deductions.

"It is rarely that these latter depend on one decision alone, even when
they are presented under the form of a single negation or affirmation.

"Deduction is always the result of many observations, formulated with
great exactness, which common sense binds together.

"That which is called a line of action is always suggested by the
analysis of the events which were produced under circumstances analogous
to those which exist now.

"From the result of these observations, the habit of thinking permits of
drawing deductions and common sense concludes the analysis.

"The method of deduction rests upon this.

"One thing being equal to a previous one should produce the same effects.

"If we find ourselves faced by an incident that our memory can assimilate
with another incident of the same kind, we must deduce the following
chain of reasoning:

"First, the incident of long ago has entailed inevitable consequences.

"Secondly, the incident of to-day ought to produce the same effects,
unless the circumstances which surround it are different.