"6. We cannot avoid repetition of the past’s mistakes
"This is an area where I have always sought to be prudent, looking at previous conflicts within the Church and within Anglicanism for indications of the way forward. My miscalculation, I think, has lain in my hope that we could in fact learn from our past mistakes! To acknowledge, as I now do, that we cannot so learn, however, is not an admission of despair. Rather, it is an embrace of the fact that faithful response to our conflict is not a matter of finding the magic bullet that will avoid the bad examples of the past. Faithful response, instead, is about confronting the sin endemic in our corrupted selves and ecclesial existences. This points us in very different directions than our usual strategic thinking, however well-informed by history. In short, the Christian historian is not after Thucidydes’ wisdom on this score, but rather Jesus’ own facing into the Last Days: you know what will happen, so be prepared, love and endure (Mt. 24:3-13)."
Ephraim Radner, "What I have learned these past five years: reflections in Advent, 2008," Anglican Communion Institute, Inc., http://www.anglicancommunioninstitute.com/?p=342#more-342. Words of wisdom from a professional historian with first-class credentials. The allusion may be to The Peloponnesian war I.i.22 ("if [my history] be judged useful by those inquirers who desire an exact knowledge of the past as an aid to the interpretation of the future, which in the course of human things must resemble if it does not reflect it, I shall be content"), I.v.123 ("'There is . . . no advantage in reflections on the past further than may be of service to the present'" (speech of the Corinthian delegation to the Second Congress at Lacedaemon)), and so forth (trans. Crawley & Feetham, GBWW, 2nd ed., vol. 5, pp. 354, 379). "Those who cannot remember the past are condemned to repeat it" the first edition of the Oxford dictionary of modern quotations attributes to Santayana (Life of reason (1905), vol. 1, chap. 12). I have not looked any harder than this.