mechanical aggregation and by those of chemical union. It is the
business of the abstract sciences, Physics and Chemistry, to ascertain
these laws: to discover how and under what conditions bodies may become
aggregated, and what are the possible modes and results of chemical
combination. The great majority of these aggregations and combinations
take place, so far as we are aware, only in our laboratories; with these
the concrete science, Mineralogy, has nothing to do. Its business is
with those aggregates, and those chemical compounds, which form
themselves, or have at some period been formed, in the natural world.
Again, Physiology, the abstract science, investigates, by such means as
are available to it, the general laws of organization and life. Those
laws determine what living beings are possible, and maintain the
existence and determine the phaenomena of those which actually exist:
but they would be equally capable of maintaining in existence plants and
animals very different from these. The concrete sciences, Zoology and
Botany, confine themselves to species which really exist, or can be
shown to have really existed: and do not concern themselves with the
mode in which even these would comport themselves under all
circumstances, but only under those which really take place. They set
forth the actual mode of existence of plants and animals, the phaenomena
which they in fact present: but they set forth all of these, and take
into simultaneous consideration the whole real existence of each
species, however various the ultimate laws on which it depends, and to
whatever number of different abstract sciences these laws may belong.
The existence of a date tree, or of a lion, is a joint result of many
natural laws, physical, chemical, biological, and even astronomical.
Abstract science deals with these laws separately, but considers each of
them in all its aspects, all its possibilities of operation: concrete
science considers them only in combination, and so far as they exist and
manifest themselves in the animals or plants of which we have