The first law for the historian is that he shall never dare utter an untruth. The second is that he shall suppress nothing that is true. Moreover, there shall be no suspicion of partiality in his writing, or of malice.
All men have a feeling, that they would rather you told them a civil lie than give them a point blank refusal.... If you make a promise, the thing is still uncertain, depends on a future day, and concerns but few people; but if you refuse you alienate people to a certainty and at once, and many people too.