e mechanical
addition of extraneous matter, as we add a pound of tea to a pound of
tea. It is true growth from within. It is the making outward of what
is inward. It is the making explicit of what is implicit. It is the
making actual of what is potential in the embryo organism.

The lowest in the scale of being is thus inorganic matter, and above
it comes organic matter, in which the principle of form becomes real
and definite as the inward organization of the thing. This inward
organization is the life, or what we call the soul, of the organism.
Even the human soul is nothing but the organization of the body. It
stands to the body in the relation of form to matter. With organism,
then, we reach the idea of living soul. But this living soul will
itself have lower and higher grades of being, the higher being a
higher realization of the principle of form. As the essential of
organism is self-realization, this will express itself first as
self-preservation. Self-preservation means first the preservation of
the individual, and this gives the function of nutrition. Secondly, it
means preservation of the species, and this gives the function of
propagation. The lowest grade in the organic kingdom will, therefore,
be {297} those organisms whose sole functions are to nourish
themselves, grow, and propagate their kind. These are plants. And we
may sum up this by saying that plants possess the nutritive soul.
Aristotle intended to write a treatise upon plants, which intention,
however, he never carried out. All that we have from him on plants is
scattered references in his other books. Had the promised treatise
been forthcoming, we cannot doubt what its plan would have been.
Aristotle would have shown, as he did in the case of animals, that
there are higher and lower grades of organism within the plant
kingdom, and he would have attempted to trace the development in
detail through all the then known species of plants.

Next above plants in the scale of being come animals. Since the higher
always contains the lower, but exhibits a further realization of form
peculiar to itself, animals share with plants the functions of
nutrition and propagation. What is peculiar to them, the point in
which they rise above plants, is the possession of sensation.
Sense-perception is therefore the special function of animals, and
they possess, therefore, the nutritive and the sensitive souls. With
sensation come pleasure and pain, for pleasure is a