§ 8. It continually happens that several different phenomena, which are
not in the slightest degree dependent or conditional on one another, are
found all to depend, as the phrase is, on one and the same agent; in other
words, one and the same phenomenon is seen to be followed by several sorts
of effects quite heterogeneous, but which go on simultaneously one with
another; provided, of course, that all other conditions requisite for each
of them also exist. Thus, the sun produces the celestial motions; it
produces daylight, and it produces heat. The earth causes the fall of
heavy bodies, and it also, in its capacity of a great magnet, causes the
phenomena of the magnetic needle. A crystal of galena causes the
sensations of hardness, of weight, of cubical form, of gray color, and
many others between which we can trace no interdependence. The purpose to
which the phraseology of Properties and Powers is specially adapted, is
the expression of this sort of cases. When the same phenomenon is followed
(either subject or not to the presence of other conditions) by effects of
different and dissimilar orders, it is usual to say that each different
sort of effect is produced by a different property of the cause. Thus we
distinguish the attractive or gravitative property of the earth, and its
magnetic property: the gravitative, luminiferous, and calorific properties
of the sun: the color, shape, weight, and hardness of a crystal. These are
mere phrases, which explain nothing, and add nothing to our knowledge of
the subject; but, considered as abstract names denoting the connection
between the different effects produced and the object which produces them,
they are a very powerful instrument of abridgment, and of that
acceleration of the process of thought which abridgment accomplishes.