Einhard

“Be this as it may, I see no reason why I should refrain from entering upon a task of this kind, since no man can write with more accuracy than I of events that took place about me, and of facts concerning which I had personal knowledge, ocular demonstration as the saying goes, and I have no means of ascertaining whether or not any one else has the subject in hand”

Einhard: The Life of Charlemagne, translated by Samuel Epes Turner, (New York: Harper & Brothers, 1880)