s_.

We shall say nothing of a metaphysical nature respecting reason, but
shall simply point to two important facts connected with its exercise.
The _first_--that it suspends or greatly modifies the action of other
powers--has already been noticed in our remarks on imagination; but we
must state it here in more distinct terms. We especially wish the
reader to understand how wide and important is the meaning of the
terms 'control' and 'overrule' as we use them when we say: 'reason
controls, or overrules, imagination!' When we say that, in nature, the
laws which regulate one stage of existence _overrule_ the laws of
another and a lower stage, we do not intend to say that the latter are
annulled, but that they are so controlled and modified in their course
of action, that they can no longer produce the effects which would
take place if they were left free from such control. A few examples
will make our meaning plain. Let us contrast the operations of
chemistry with those of mechanism. In the latter, substances act upon
each other simply by pressure, motion, friction, &c.; but in
chemistry, affinities and combinations come into play, producing
results far beyond any that are seen in mechanics. On mechanical
principles, the trituration of two substances about equal in hardness
should simply reduce them to powder, but in chemistry, it may produce
a gaseous explosion. Again--vegetable life overrules chemistry: the
leaves, twigs, and branches of a tree, if left without life, would,
when exposed to the agencies of air, light, heat, and moisture, be
partly reduced to dust and partly diffused as gas in the atmosphere.
It is the vegetative life of the tree which controls both the
mechanical and the chemical powers of wind, rain, heat, and
gravitation; and it is not until the life is extinct that these
inferior powers come into full play upon the tree. So, again, the
animal functions control chemical laws--take digestion, for example: a
vegetable cut up by the root and exposed to the air, passes through a
course of chemical decomposition, and _is_ finally converted into gas;
but when an animal consumes a vegetable, it is not decomposed
according to the chemical laws, but is digested, becomes chyle, and is
assimilated to the body of the animal. It is obvious that animal life
controls mechanical laws. Thus, the friction of two inert substances
wears one of them away--the soft yields to the hard; but, on the
contrary, the hand of the