 Monastic psychology also made use of the originally Stoic doctrine of first movements, which Origen, followed by Augustine and many others, applied to the Christian conception of sin. The Stoic idea, described by Seneca in On Anger (2.1–4), was that even apathetic people might react quasi-emotionally on exceptional occasions, but this was not really an emotion because it did not involve judgmental assent. Augustine taught that sinful thoughts which easily and frequently came to mind because of original sin became sins through a subsequent assent (Expositio quarundam propositionum ex Epistola ad Romanos, 2066).