bordinate powers, each with a less range of duties and capacities
than those of higher estate, until at the bottom of the system there
were minor deities and demigods charged with the management of the
trees, the flowers, and the springs--creatures differing little from
man, except that they were immortal, and generally invisible, though
they, like all the other deities, might at their will display
themselves to the human beings over whom they watched, and whose path
in life they guided.

Among only one people do we find that the process of advance led
beyond this early and simple method of accounting for the processes of
Nature, bringing men to an understanding such as we now possess. This
great task was accomplished by the Greeks alone. About twenty-five
hundred years ago the philosophers of Greece began to perceive that
the early notion as to the guidance of the world by creatures
essentially like men could not be accepted, and must be replaced by
some other view which would more effectively account for the facts.
This end they attained by steps which can not well be related here,
but which led them to suppose separate powers behind each of the
natural series--powers having no relation to the qualities of mankind,
but ever acting to a definite end. Thus Plato, who represents most
clearly this advance in the interpretation of facts, imagined that
each particular kind of plant or animal had its shape inevitably
determined by something which he termed an idea, a shape-giving power
which existed before the object was created, and which would remain
after it had been destroyed, ever ready again to bring matter to the
particular form. From this stage of understanding it was but a short
step to the modern view of natural law. This last important advance
was made by the great philosopher Aristotle, who, though he died about
twenty-two hundred years ago, deserves to be accounted the first and
in many ways the greatest of the ancient men of science who were
informed with the modern spirit.

With Aristotle, as with all his intellectual successors, the
operations of Nature were conceived as to be accounted for by the
action of forces which we commonly designate as natural laws, of which
perhaps the most familiar and universal is that of gravitation, which
impels all bodies to move toward each other with a degree of intensity
which is measured by their weight and the distance by which they are
separated.

For many centuries s