or as it exists in the lowest order of animals, involve or explain? How,
for instance, does it include sensation, locomotion, or habit? or if the
two former should be taken as distinct from life, _toto genere_, and
supervenient to it, we then ask what conception is given of _vital_
assimilation as contradistinguished from that of the nucleus of a crystal?

_Lastly_, this definition confounds the Law of Life, or the primary and
universal form of vital agency, with the conception, Animals. For the
kind, it substitutes the representative of its degrees and modifications.
But the first and most important office of science, physical or
physiological, is to contemplate the power in kind, abstracted from the
degree. The ideas of caloric, whether as substance or property, and the
conceptions of latent heat, the heat in ice, &c., that excite the wonder
or the laughter of the vulgar, though susceptible of the most important
practical applications, are the result of this abstraction; while the only
purpose to which a definition like the preceding could become subservient,
would be in supplying a nomenclature with the character of the most common
species of a genus--its _genus generalissimum_, and even this would be
useless in the present instance, inasmuch as it presupposes the knowledge
of the things characterised.

The third class, and far superior to the two former, selects some property
characteristic of all living bodies, not merely found in all _animals_
alike, but existing equally in all parts of all living things, both
animals and plants. Such, for instance, is the definition of Life, as
consisting in anti-putrescence, or the power of resisting putrefaction.
Like all the others, however, even this confines the idea of Life to those
degrees or concentrations of it, which manifest themselves in organized
beings, or rather in those the organization of which is apparent to us.
Consequently, it substitutes an abstract term, or generalization of
effects, for the idea, or superior form of causative agency. At best, it
describes the _vis vita_ by one only of its many influences. It is
however, as we have said before, preferable to the former, because it is
not, as they are, altogether unfruitful, inasmuch as it attests, less
equivocally than any other sign, the presence or absence of that degree of
the _vis vita_ which is the necessary condition of organic or
self-renewing power. It throws no light, however, on the law or principle