W. Montgomery Watt

"His readiness to undergo persecutions for his beliefs, the high moral character of the men who believed in him and looked up to him as leader, and the greatness of his ultimate achievement - all argue his fundamental integrity. To suppose Muhammad an impostor raises more problems than it solves. Moreover, none of the great figures of history is so poorly appreciated in the West as Muhammad."

Mohammad at Mecca, Oxford 1953, p. 52