 There is no record of any response by Arnauld to the Confessio Philosophi, but when Leibniz returned to the problems of theodicy, in 1686, he once again sought Arnauld’s cooperation by sending Arnauld the outline of the Discourse on Metaphysics that was mentioned above. The outline sent to Arnauld was no more than a list of the propositions that were to appear as the titles of the thirty-seven sections of the Discourse; the entire correspondence was carried out through the intermediary of Hessen-Rheinfels; and the copies of letters received by the two major correspondents were sometimes defective. These facts, together with the extreme subtlety of the philosophical contents of the letters, have made interpretation of the correspondence very difficult.