Hi, Dr Loving--

I found it in chapter 18.....

"DURING the two or two and a half years of my apprenticeship,
I served under many pilots, and had experience of many
kinds of steamboatmen and many varieties of steamboats;
for it was not always convenient for Mr. Bixby to have me
with him, and in such cases he sent me with somebody else.
I am to this day profiting somewhat by that experience;
for in that brief, sharp schooling, I got personally and familiarly
acquainted with about all the different types of human nature
that are to be found in fiction, biography, or history.
The fact is daily borne in upon me, that the average shore-employment
requires as much as forty years to equip a man with this sort
of an education.  When I say I am still profiting by this thing,
I do not mean that it has constituted me a judge of men--
no, it has not done that; for judges of men are born, not made.
My profit is various in kind and degree; but the feature of it
which I value most is the zest which that early experience has
given to my later reading.  When I find a well-drawn character
in fiction or biography, I generally take a warm personal
interest in him, for the reason that I have known him before--
met him on the river."