Gustave Flaubert on travel books

Only, travel writing as a genre is per se almost impossible.  To eliminate all repetitions you would have had to refrain from telling what you saw.  This is not the case in books devoted to descriptions of discoveries, where the author’s personality is the focus of interest.  But in the present instance the attentive reader may well find that there are too many ideas and insufficient facts, or too many facts and not enough ideas.

That is from his November 1866 letter to Hippolyte Taine, reproduced in the Francis Steegmuller collection.  Here is my recent post on why most travel books are not good enough.  Here is a 2006 MR post on which are the best travel books.