“I think I have seen with impartial eyes, and I am sure I have written at least honestly, whether wisely or not.”
Twain distinguishes honest reporting from a claim to perfect judgment, presenting candor and acknowledged fallibility as part of his travel-writing method.
Source details
The Innocents Abroad (1869), Preface. Twain says that he thinks he has seen with impartial eyes and is sure he has written honestly, while explicitly declining to claim perfect wisdom. Verified against the scan-backed 1869 first edition on Wikisource, original Preface page 19; this is authorial travel-writing method rather than a claim of objective infallibility.