'RDostai bar R' Yannai says in the name of Rabbi Meir: Anyone who forgets one item of his studies, Scripture considers it as if he bears guilt for his soul, as it is stated: Only beware for yourself and greatly beware for your soul, lest you forget the things that your eyes have beheld. I might think even if his studies overwhelmed him; Scripture [therefore] states (ibid.): and lest you remove them from your heart all the days of your life. Thus he does not bear guilt for his soul unless he sits and removes them from his heart.