Mark Twain quote about his father's surprising maturation (antedating attrib circa 1915) (req paper verification)

[Garson O'Toole]

Thank you for your responses. I have found another example that
appeared before the Reader's Digest citation. This 1930 cite is
full-text accessible at the Internet Archive, and it is similar to the
one appearing in the conference of Women Deans, Administrators &
Counselors. The young son is initially seventeen instead of fourteen,
and he ages in two steps to twenty-five instead of twenty-one.

The quote and its Twain attribution appear to be part of "extracts
from a sermon delivered by President Gray of Bates College."

Citation: 1930 October, Journal of Social Hygiene, Page 437, Vol. XVI,
No. 7, News and Abstracts, Youth's Problems are Old as the World.

Nearly two generations ago, Mark Twain told how, when he was
seventeen, he could hardly bear to be with his father, because the
latter was so ignorant; at twenty he noticed that now and then his
father said a sensible thing, but at twenty-five he was simply amazed
to discover how his father had improved in the last eight years. After
all there is little difference between the 1850's and the 1930's.

http://www.archive.org/details/journalofsocialh16amerrich
http://www.archive.org/stream/journalofsocialh16amerrich#page/436/mode/2up/search/amazed

Google Books has a snippet-restricted version of the document.
http://books.google.com/books?id=NvkVAQAAIAAJ&
http://books.google.com/books?id=NvkVAQAAIAAJ&q=Twain#search_anchor

Garson

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