the former, and to be moved by a power altogether different, though
many of the works and operations are, he admits, common to both
machines. In this supposed peculiarity he places the essential
character of the former machine, and defines it by the presence of
that which is, or which he supposes to be, absent in the latter.
Supposing that a stranger to both were about to visit the two
machines, this peculiarity would be so far useful as that it might
enable him to distinguish the one from the other, and thus to look
in the proper place for whatever else he had heard remarkable
concerning either; not that he or his informant would understand the
machine any better or otherwise, than the common character of a
whole class in the nomenclature of botany would enable a person to
understand all, or any one of the plants contained in that class.
But if, on the other hand, the machine in question were such as no
man was a stranger to, if even the supposed peculiarity, either by
its effects, or by the construction of that portion of the works
which produced them, were equally well known to all men, in this
case we can conceive no use at all of such a definition; for at the
best it could only be admitted as a definition for the purposes of
nomenclature, which never adds to knowledge, although it may often
facilitate its communication. But in this instance it would be
nomenclature misplaced, and without an object. Such appears to me to
be the case with all those definitions which place the essence of
Life in nutrition, contractility, &c. As the second instance, I will
take the inventor and maker of the machine himself, who knows its
moving power, or perhaps himself constitutes it, who is, as it were,
the soul of the work, and in whose mind all its parts, with all
their bearings and relations, had pre-existed long before the
machine itself had been put together. In him therefore there would
reside, what it would be presumption to attempt to acquire, or to
pretend to communicate, the most perfect insight not only of the
machine itself, and of all its various operations, but of its
ultimate principle and its essential causes. The mysterious ground,
the efficient causes of vitality, and whether different lives differ
absolutely or only i