The commission with which you charged us, O holy man of God, Theodore, we have executed in the five foregoing books; in which to the best of our ability, we have comprised the history of the Church from the time of Constantine. Notice, however, that we have been by no means studious of style; for we considered that had we showed too great fastidiousness about elegance of expression we might have defeated the object in view. But even supposing our purpose could still have been accomplished, we were wholly precluded from the exercise of that discretionary power of which ancient historians seem to have so largely availed themselves, whereby any one of them imagined himself quite at liberty to amplify or curtail matters of fact. Moreover, refined composition would by no means be edifying to the masses and illiterate men, who are intent merely on knowing the facts, and not on admiring beauty of diction. In order therefore not to render my production unprofitable to both classes of readers—to the learned on the one hand, because no elaboration of language could satisfy them to rank it with the magniloquence of the writers of antiquity, and to the unlearned on the other, because they could not understand the facts, should they be clouded by a parade of words—we have purposely adopted a style, divested indeed of all affectation of sublimity, but at the same time clear and perspicuous.
As we begin, however, our sixth book, we must premise this, that in undertaking to detail the events of our own age, we are apprehensive of advancing such things as may be unpalatable to many: either because, according to the proverb, 'Truth is bitter;' on account of our not mentioning with encomium the names of those whom some may love; or from our not magnifying their actions. The zealots of our churches will condemn us for not calling the bishops 'Most dear to God,' 'Most holy,' and such like. Others will be litigious because we do not bestow the appellations 'Most divine,' and 'Lords' on the emperors, nor apply to them such other epithets as they are commonly assigned. But since I could easily prove from the testimony of ancient authors, that among them the servant was accustomed to address his master simply by name, without reference to his dignity or titles, on account of the pressure of business, I shall in like manner obey the laws of history, which demand a simple and faithful narration, unobscured by a veil of any kind. I shall proceed to record accurately what I have either myself seen, or have been able to ascertain from actual observers; having tested the truth by the unanimity of the witnesses that spoke of the same affairs, and by every means I could possibly command. The process of ascertaining the truth was indeed laborious, inasmuch as many and different persons gave different accounts and some claimed to be eyewitnesses, while others professed to be more intimately acquainted with these things than any others.
Source: Ecclesiastical History (New Advent)