bjection to your
miracle. And our reply to the levitators is just the same. Why should
not your friend "levitate"? Fish are said to rise and sink in the
water by altering the volume of an internal air-receptacle; and there
may be many ways science, as yet, knows nothing of, by which we, who
live at the bottom of an ocean of air, may do the same thing.
Dialectic gas and wind appear to be by no means wanting among you, and
why should not long practice in pneumatic philosophy have resulted in
the internal generation of something a thousand times rarer than
hydrogen, by which, in accordance with the most ordinary natural laws,
you would not only rise to the ceiling and float there in
quasi-angelic posture, but perhaps, as one of your feminine adepts is
said to have done, flit swifter than train or telegram to
"still-vexed Bermoothes," and twit Ariel, if he happens to be there,
for a sluggard? We have not the presumption to deny the possibility of
anything you affirm; only, as our brethren are particular about
evidence, do give us as much to go upon as may save us from being
roared down by their inextinguishable laughter.

Enough of the realism which clings about "laws." There are plenty of
other exemplifications of its vitality in modern science, but I will
cite only one of them.

This is the conception of "vital force" which comes straight from the
philosophy of Aristotle. It is a fundamental proposition of that
philosophy that a natural object is composed of two constituents--the
one its matter, conceived as inert or even, to a certain extent,
opposed to orderly and purposive motion; the other its form, conceived
as a quasi-spiritual something, containing or conditioning the actual
activities of the body and the potentiality of its possible
activities.

I am disposed to think that the prominence of this conception in
Aristotle's theory of things arose from the circumstance that he was
to begin with and throughout his life, devoted to biological studies.
In fact it is a notion which must force itself upon the mind of any
one who studies biological phenomena, without reference to general
physics, as they now stand. Everybody who observes the obvious
phenomena of the development of a seed into a tree, or of an egg into
an animal, will note that a relatively formless mass of matter
gradually grows, takes a definite shape and structure, and, finally,
begins to perform actions which contribute towards a certain end,
namely