George Lewis, The Philocalia of Origen, Edinburgh: T. & T. Clark, 1911. Translator's preface: "The wholesale destruction of his writings which followed upon the warfare waged against his opinions shortly after his death, has caused a special value to attach to the Philocalia as preserving to us in the original much of Origen's work which would otherwise have been entirely lost, or would have survived only in the translations of Rufinus. Moreover, even his great and comparatively popular work against Celsus depends for its text solely on a manuscript of the thirteenth century, so that we have a cause for gratitude in the preservation of a large part of it in the Philocalia."
See translation of the Greek introduction in George Lewis' translation here.
