no
influence upon the process but only obscure it; as when, being pleased
with a certain scent in a garden, we wish to know from what flower it
rises; or, being attracted by the sound of some instrument in an
orchestra, we desire to know which it is: or (2) amidst circumstances
that alter the effect from what it would have been by the sole operation
of some cause; as when the air deflects a falling feather; or in some
more complex case, such as a rise or fall of prices that may extend over
many years.

To begin with, we must form definite ideas as to what the phenomenon is
that we are about to investigate; and in a case of any complexity this
is best done by writing a detailed description of it: e.g., to
investigate the cause of a recent fall of prices, we must describe
exactly the course of the phenomenon, dating the period over which it
extends, recording the successive fluctuations of prices, with their
maxima and minima, and noting the classes of goods or securities that
were more or less affected, etc.

Then the first step of elimination (as Bain further observes) is "to
analyse the situation mentally," in the light of analogies suggested by
our experience or previous knowledge. Dew, for example, is moisture
formed upon the surface of bodies from no apparent source. But two
possible sources are easily suggested by common experience: is it
deposited from the air, like the moisture upon a mirror when we breathe
upon it; or does it exude from the bodies themselves, like gum or
turpentine? Or, again, as to a fall of prices, a little experience in
business, or knowledge of Economics, readily suggests two possible
explanations: either cheaper production in making goods or carrying
them; or a scarcity of that in which the purchasing power of the chief
commercial nations is directly expressed, namely, gold.

Having thus analysed the situation and considered the possibility of
one, two, three, or more possible causes, we fix upon one of them for
further investigation; that is to say, we frame an hypothesis that this
is the cause. When an effect is given to find its cause, an inquirer
nearly always begins his investigations by thus framing an hypothesis as
to the cause.

The next step is to try to _verify_ this Hypothesis. This we may
sometimes do by _varying the circumstances_ of the phenomenon, according
to the Canons of direct Inductive Proof to be discussed in the next
chapter; that is to say, by _observing_ or _ex