Richard Chenevix Trench, a late 19th century Archbishop of Dublin, observed two common problems with Church histories: (1) they are so focused on details that the reader “cannot see the city for the houses,” and (2) they are so broad that they are “very often hungry, barren, dry skeletons from which all that constitutes the flesh and blood of history has been ruthlessly stripped away. ["Lecture I: On the Study of Church History," in Lectures on Medieval Church History (London: MacMillan and Co., 1879), pp. 2-3].
The latter Trench identifies as good examples of the Medieval proverb “compendia dispendia,” or, roughly, “abridgments are losses.” To avoid this error, Trench suggests that the operating question should not be “How much can I put into my story?”, but “What can I omit, and yet at the same time effectually tell that story?” The historian’s account should not be “wasted on trivialities, such as would inevitably be forgotten almost as soon as heard, on persons or events of little or no ultimate significance, however they may have filled the world with their noise for a while…” [Ibid., pg. 4].
Another problem Trench sees is the device of dividing the larger story of Church history into centuries. Of this scheme he says, “The great movements of the Church very awkwardly adapt themselves to it; often they do not adapt themselves at all, altogether traverse and ignore it.” [Ibid., pg. 5.] His own solution to this problem is to “[subordinate] the chronological order and sequence of events to the higher interests of my story.” The “laws of time” should not be so important to the Church historian that he winds up making his subject matter occupy a Procrustean bed of his own making [Ibid., pp. 5-6].
Another fault Trench observes is when Church historians fail to hold together two parables of Christ which He told back to back: the parable of the leaven working inwardly, and the parable of the Mustard seed which grows to fill the whole earth (Matt. 13:31-33). There is problem with Church historians who either tell us of the Gospel but not the Gospel of the Kingdom or who tell us of the Gospel of the Kingdom but not of the Gospel. But if the Church historian remembers both parables, and tries to hold them together in his work, he will avoid mere one sidedness and distortion of the history of redemption [Ibid., pp. 7-8].
A fourth problem sometimes emerges when Church historians either merge Church history into profane history, forgetting that “the world exist for the Church,” or else “forget that the Church exists for the world.” Church history properly told is “a divine history” in which “what therefore we are to look for first and chiefly are the vestiges of God, the print of his footsteps in it.” Yet at the same time, Church history is not the history of “an institution which will know nothing of the world, which in fact has been separated off from the world to the end that the one might be saved, and the other perish.” Instead, Church history is the story of an institution “whose separation from the world exists as much for the world’s sake as for the Church’s own, that so there may be for the world a City of Refuge, an abiding witness in the midst of it for a higher life than its own.” [Ibid., pp. 8-9].
Lastly, Church historians should always remember that the Church on earth is militant, and therefore that there will always in every age be tokens of both success and failure. In some ages, the tokens of success will appear more brightly while in others the tokens of failure. The Church is “the imperfect embodiment of a divine idea,” and “taking its history for what it most truly is, an Acta Sanctorum,” we must not forget that “it is something very different from this as well” [Ibid., pp. 11-12].