I argue that, paradoxically, Augustine embraced much of Origen’s system, especially in his anti-Manichaean polemic, exactly when he was convinced that he did not know his thought. The most remarkable point in his initial adherence to Origen’s ideas regards the apokatastasis doctrine, which he later condemned as heretical and felt the need to recant in his Retractationes (Second Thoughts). I point out many other elements of contact concerning philosophical arguments and Biblical exegesis, which the early Augustine drew from Origen and have escaped scholars who have investigated the Origen-Augustine relationship. With this I shall hopefully add an important piece to the study of Origen’s influence on Western Patristics. I thus explain how Augustine used Origen’s thought in defense of Christian orthodoxy against the Manichaean “heresy,” whereas, after he was informed about Origen’s thought by Horosius and Jerome, he began to find it heretical and condemned it, especially in De civitate Dei (The City of God) and De haeresibus (On Heresies), where he shows that he was misinformed about it. A remarkable role in this transformation was played by Augustine’s anti-Pelagian polemic: several of his expressions of blame directed against Origen’s ideas are found in his anti-Pelagian works. Another notable factor was Augustine’s ignorance of the important semantic distinction between αἰώνιος and ἀΐδιος, which got lost in the translation of both with aeternus. Moreover, I endeavor to clarify the ways and sources through which Augustine came to know Origen’s true thought when he did adhere to it, probably without being aware that it was Origen’s.