ing
than it is with us. A great physiologist, well known among us, long ago
expressed to me the same opinion; and one of the greatest of living
naturalists, who is honored alike on both continents, is positive that
brain-work is harder and more hurtful here than abroad, an opinion which
is shared by Oliver Wendell Holmes and other competent observers.
Certain it is that our thinkers of the classes named are apt to break
down with what the doctor knows as cerebral exhaustion,--a condition in
which the mental organs become more or less completely incapacitated for
labor,--and that this state of things is very much less common among the
savans of Europe. A share in the production of this evil may perhaps be
due to certain general habits of life which fall with equal weight of
mischief upon many classes of busy men, as I shall presently point out.
Still, these will not altogether account for the fact, nor is it to my
mind explained by any of the more obvious faults in our climate, nor yet
by our habits of life, such as furnace-warmed houses, hasty meals, bad
cooking, or neglect of exercise. Let a man live as he may, I believe he
will still discover that mental labor is with us more exhausting than we
could wish it to be. Why this is I cannot say, but it is not more
mysterious than the fact that agents which, as sedatives or excitants,
affect the great nerve-centres, do this very differently in different
climates. There is some evidence to show that this is also the case with
narcotics; and perhaps a partial explanation may be found in the manner
in which the excretions are controlled by external temperatures, as well
as by the fact which Dr. Brown-Sequard discovered, and which I have
frequently corroborated, that many poisons are retarded in their action
by placing the animal affected in a warm atmosphere.

It is possible to drink with safety in England quantities of wine which
here would be disagreeable in their first effect and perilous in their
ultimate results. The Cuban who takes coffee enormously at home, and
smokes endlessly, can do here neither the one nor the other to the same
degree. And so also the amount of excitation from work which the brain
will bear varies exceedingly with variations of climatic influences.

We are all of us familiar with the fact that physical work is more or
less exhausting in different climates, and as I am dealing, or about to
deal, with the work of business men, which involves a certain