A thorough study of Human Physiology is, in itself, an education broader
and more comprehensive than much that passes under that name. There is
no side of the intellect which it does not call into play, no region
of human knowledge into which either its roots, or its branches, do not
extend; like the Atlantic between the Old and the New Worlds, its waves
wash the shores of the two worlds of matter and of mind; its tributary
streams flow from both; through its waters, as yet unfurrowed by the
keel of any Columbus, lies the road, if such there be, from the one to
the other; far away from that North-west Passage of mere speculation, in
which so many brave souls have been hopelessly frozen up.