self--as ours to experiment with and to speculate upon. Casting
the term "vital force" from our vocabulary, let us reduce, if we can,
the visible phenomena of life to mechanical attractions and
repulsions. Having thus exhausted physics, and reached its very rim, a
mighty Mystery still looms beyond us. We have, in fact, made no step
towards its solution. And thus it will ever loom, compelling the
philosophies of successive ages to confess that

"We are such stuff
As dreams are made of, and our little life
Is rounded by a sleep."

In my work on 'Heat,' published in 1863 and republished many times
since, I employ the precise language thus extracted from the 'Saturday
Review.'

The distinction is here clearly brought out which I had resolved at
all hazards to draw--that, namely, between what men knew or might
know, and what they could never hope to know. Impart simple
magnifying power to our present vision, and the atomic motions of the
brain itself might be brought into view. Compare these motions with
the corresponding states of consciousness, and an empirical nexus
might be established; but 'we try to soar in a vacuum when we
endeavour to pass by logical deduction from the one to the other.'
Among these brain-effects a new product appears which defies
mechanical treatment. We cannot deduce motion from consciousness or
consciousness from motion as we deduce one motion from another.
Nevertheless observation is open to us, and by it relations may be
established which are at least as valid as those of the deductive
reason. The difficulty may really lie in the attempt to convert a
datum into an inference--an ultimate fact into a product of logic. My
desire for the moment, however, is not to theorise, but to let facts
speak in reply to accusation.

The most 'materialistic' speculation for which I was responsible,
prior to the 'Belfast Address,' is embodied in the following extract
from a brief article written as far back as 1865: 'Supposing the
molecules of the human body, instead of replacing others, and thus
renewing a pre-existing form, to be gathered first-hand from nature,
and placed in the exact relative positions which they occupy in the
body. Supposing them to have the same forces and distribution of
forces, the same motions and distribution of motions--would this
organised concourse of molecules stand before us as a sentient,
thinking being? There seems no valid reason