Gregg,
The full quote reads as follows:
``You perceive I generalize with intrepidity from single
instances. It is the tourists' custom. When I see a man jump
from the Vendome Column I say, 'They like to do that in
Paris.'''
It appears in _Mark Twain's Notebooks & Journals, Vol. II._ page 318. Also
in Paine, Chapter 121 (Vol. II), page 644.
Kevin B.