Arukh HaShulchan, Orach Chaim 249:2-9

Sugya Map

• Issue: The permissibility of writing on Chol HaMoed, specifically regarding chiddushei Torah.
• Nafka Mina(s): When does the principle of "דבר האבד" (a matter that would be lost) apply to allow otherwise forbidden writing? What level of potential forgetfulness qualifies?
• Primary Sources: Mishna Moed Katan 18b, Gemara Moed Katan 18b-19a, Shulchan Arukh Orach Chaim 545:1, Rema Orach Chaim 545:1, Magen Avraham 545:1, Arukh HaShulchan Orach Chaim 249:2-9.

Text Snapshot

The Arukh HaShulchan sharpens the definition of "דבר האבד":

"ומ"מ בדבר האבד היינו דוקא דבר שאם לא יכתוב עכשיו יאבד לגמרי ואם יכול לזכור אח"כ אף שיש חשש שישכח איזה פרט או איזה דיוק אינו נקרא דבר האבד." "ולכן בחידושי תורה אסור לכתוב בחול המועד אא"כ הוא דבר שחושש שיאבד ממנו לגמרי ולא יוכל לזכור אותו אח"כ כלל." (Arukh HaShulchan, Orach Chaim 249:7-8)

• Dikduk/Leshon Nuance: The repeated intensification with "לגמרי" (completely) and "כלל" (at all) is crucial. It differentiates a total, irrecoverable loss from mere forgetting of "איזה פרט או איזה דיוק" (some detail or nuance).

Readings

• Rema (OC 545:1): Permits writing chiddushei Torah on Chol HaMoed if "יכול לשכחו" (one might forget it). This appears a broader leniency.
• Magen Avraham (545:1): Reinterprets Rema's "יכול לשכחו" as referring specifically to a case where one "ישכחנו לגמרי" (will forget it completely), thereby significantly narrowing the scope of the Rema's leniency. The Arukh HaShulchan explicitly adopts this stricter interpretation.

Friction

• Kushya: The Rema's simple wording "יכול לשכחו" seems to allow writing chiddushei Torah even for less than total forgetfulness. How does the Arukh HaShulchan's strict interpretation of "לגמרי" align?
• Terutz: The Arukh HaShulchan doesn't contradict the Rema, but rather clarifies and adopts the Magen Avraham's restrictive reading of the Rema. For the Arukh HaShulchan, the Magen Avraham's understanding is the Rema's intended psak, thereby harmonizing the seemingly disparate views by defining "forgetting" as absolute loss.

Intertext

• Moed Katan 18b: The Gemara introduces the concept of "דבר האבד" permitting writing, e.g., "אין כותבין ספרי חשבונות" (one does not write account books) unless for a "דבר האבד."
• Rambam, Hilchot Yom Tov 8:14: "וכן כל דבר שאם ימתין עד לאחר המועד יבא לידי הפסד... הרי זה מותר" (And similarly, any matter that if delayed until after the holiday would result in loss... is permitted). This establishes the general principle of davar ha'oved.

Psak/Practice

The Arukh HaShulchan's stringent definition of davar ha'oved for chiddushei Torah sets a high bar. One should generally refrain from writing Torah novellae on Chol HaMoed unless there is a genuine, existential fear of the complete and irreversible loss of the idea, not merely the forgetting of a detail or precise wording. This impacts contemporary talmidei chachamim regarding shiur preparation or sudden insights during the holiday.

Takeaway

The Arukh HaShulchan, following the Magen Avraham, narrowly defines "דבר האבד" for chiddushei Torah on Chol HaMoed, allowing writing only in cases of imminent, complete intellectual extinction, elevating the sanctity of Chol HaMoed over minor mnemonic concerns.