shed from all the
phenomena of sensation, that, whilst the latter are particular,
contingent, and relative, the former are _universal_, _necessary_, and
_absolute_. As an example, and a proof of the reality and validity of
this distinction, take the ideas of _body_ and of _space_, the former
unquestionably derived from experience, the latter supplied by reason
alone. "I ask you, can not you conceive this book to be destroyed?
Without doubt you can. And can not you conceive the whole world to be
destroyed, and no matter whatever in existence? You can. For you,
constituted as you are, the supposition of the non-existence of bodies
implies no contradiction. And what do we call the idea of a thing which
we can conceive of as non-existing? We call it a _contingent_ and
_relative_ idea. But if you can conceive this book to be destroyed, all
bodies destroyed, can you suppose space to be destroyed? You can not. It
is in the power of man's thought to conceive the non-existence of
bodies; it is not in the power of man's thought to conceive the
non-existence of space. The idea of space is thus a _necessary_ and
_absolute_ idea."[224]

[Footnote 224: Cousin's "Hist. of Philos.," vol. ii. p. 214.]

Take, again, the ideas of _event_ and _cause_. The idea of an event is a
_contingent_ idea; it is the idea of something which might or might not
have happened. There is no impossibility or contradiction in either
supposition. The idea of cause is a _necessary_ idea. An event being
given, the idea of cause is necessarily implied. An uncaused event is an
impossible conception. The idea of cause is also a _universal_ idea
extending to all events, actual or conceivable, and affirmed by all
minds. It is a rational fact, attested by universal consciousness, that
we can not think of an event transpiring without a cause; of a thing
being the author of its own existence; of something generated by and out
of nothing. _Ex nihilo nihil_ is a universal law of thought and of
things. This universal "law of causality" is clearly distinguishable
from a _general_ truth reached by induction. For example, it is a very
general truth that, during twenty-four hours, day is succeeded by night.
But this is not a necessary truth, neither is it a universal truth. It
does not extend to all known lands, as, for example, to Nova Zembla. It
does not hold true of the other planets. Nor does it extend to all
possible lands. We can easily conceive of lands plunged in ete