“Yet with every allowance, one feels it difficult to see how any mortal ever could consider this Koran as a Book written in Heaven, too good for the Earth; as a well-written book, or indeed as a book at all; and not a bewildered rhapsody; written, so far as writing goes, as badly as almost any book ever was!”

Trash, Violence, and Versace: But Is It Art? http://www.city-journal.org/html/8_1_urbanities-trash.html (Winter 1998). <br class="br">City Journal (1998 - 2008)

From Why You Should Never be a Christian (1987) by Ishaq 'Kunle Sanni and ‎Dawood Ayodele Amoo.
Misattributed

Source: The Bed of Procrustes: Philosophical and Practical Aphorisms

Variant: [I]f a book is well written, I always find it too short.
Source: Sense and Sensibility

Sermon (1899)

Preface
Alone (1938)
Context: This book is the account of a personal experience — so personal that for four years I could not bring myself to write it. It is different from anything else I have ever written. My other books have been factual, impersonal narratives of my expeditions and flights. This book, on the other hand, is the story of an experience which was in considerable part subjective. I very nearly died before it was over.