take down my "American
Cyclopaedia" and borrow instruction from the learned articles of Dr.
Kneeland, I cease to regret that his indefatigable and intelligent
industry was turned into a broader channel. And what can I say too
cordial of my long associated companion and friend, Dr. Hodges, whose
admirable skill, working through the swiftest and surest fingers that
ever held a scalpel among us, has delighted class after class, and filled
our Museum with monuments which will convey his name to unborn
generations?

This day belongs, however, not to myself and my recollections, but to all
of us who teach and all of you who listen, whether experts in our
specialties or aliens to their mysteries, or timid neophytes just
entering the portals of the hall of science. Look in with me, then,
while I attempt to throw some rays into its interior, which shall
illuminate a few of its pillars and cornices, and show at the same time
how many niches and alcoves remain in darkness.

SCIENCE is the topography of ignorance. From a few elevated points we
triangulate vast spaces, inclosing infinite unknown details. We cast the
lead, and draw up a little sand from abysses we may never reach with our
dredges.

The best part of our knowledge is that which teaches us where knowledge
leaves off and ignorance begins. Nothing more clearly separates a vulgar
from a superior mind, than the confusion in the first between the little
that it truly knows, on the one hand, and what it half knows and what it
thinks it knows on the other.

That which is true of every subject is especially true of the branch of
knowledge which deals with living beings. Their existence is a perpetual
death and reanimation. Their identity is only an idea, for we put off
our bodies many times during our lives, and dress in new suits of bones
and muscles.

"Thou art not thyself;
For thou exist'st on many a thousand grains
That issue out of dust."

If it is true that we understand ourselves but imperfectly in health,
this truth is more signally manifested in disease, where natural actions
imperfectly understood, disturbed in an obscure way by half-seen causes,
are creeping and winding along in the dark toward their destined issue,
sometimes using our remedies as safe stepping-stones, occasionally, it
may be, stumbling over them as obstacles.

I propose in this lecture to show you some points of contact between our
ignorance and our knowledge in several of th