תלמוד על משלי 7:3

Rabban Shimon ben Gamliel then added to what he said: One who studies Torah in his youth is like a young man who married a young woman. She was a good match for him, and he a good match for her. And she cast herself upon him, and he cast himself upon her. One who studies Torah in his old age, what is he like? Like an old man who married a young woman. She was a good match for him, but he was not a good match for her. She cast herself upon him, but he kept his distance from her, as it says (Psalms 127:4–5), “Like arrows in the hand of a warrior are children of youth.” And immediately afterward it says, “Happy is the man who fills his quiver with them.” One who learns and then forgets is like a woman who gives birth to children and then buries them, as it says (Hosea 9:12), “Even though they raise children, I will bereave people of them.” Do not read “bereave” (v’sikaltim), but rather, “cause them to forget” (v’shikhahtim).
(Rabbi Shimon ben Elazar would say: One who studies Torah in his youth is like a doctor who is treating a wound, and has a scalpel to cut into it and medicine to heal it. One who studies Torah in his old age is like a doctor who is treating a wound, and has a scalpel to cut into it but no medicine to heal it. So it is with words of Torah: they) are marked [in order for an individual] to distinguish one from one another, and then arranged side by side, as it says (Proverbs 7:3), “Tie them to your fingers and write them on the tablet of your heart.” And also (Proverbs 6:21), “Tie them to your heart always, and fasten them around your throat.”