(Mishnah): Concerning the beginnings of rows - the sheaf opposite it proves it. (This will soon be explained.) If the owner took a sheaf intending to bring it to the city and he forgot it, it is not Shichechah.

These are considered the beginnings of rows - if two people began (gathering) from the middle of the row, with one facing northwards and one facing southwards (moving away from each other) and they forgot (sheaves) - those forgotten in front of them are Shichechah; behind them are not Shichechah.

If an individual started at the beginning of the row and forgot sheaves, those forgotten before him are not Shichechah, after him are Shichechah, as it is included in the phrase (Devarim 24:19), "you shall not go back (to take it)".

The general rule is - anything included in "you shall not go back" is Shichechah; anything that is not included in "you shall not go back" is not Shichechah.

(Gemara) Question: What is the source that the beginnings of rows are not Shichechah?

Answer (R. Yona): The pasuk states (Devarim 24:19), "When you shall reap your harvest in the field and you shall forget" - from where you begin to harvest can be Shichechah.

Question: This only teaches the beginnings of rows of standing crops; what about the ends of rows of (detached) sheaves?

Answer (R. Yona): The same pasuk states, "you shall not go back to take it".

Question: This only teaches the beginnings of rows of standing crops and the ends of rows of sheaves; what about the beginnings of the rows of sheaves and the ends of rows of standing crops?

Answer (R. Yona): Let's learn beginnings of the rows of sheaves from beginnings of rows of standing crops and learn the ends of rows of standing crops from the ends of the rows of sheaves.

The Mishnah taught: The sheaf opposite it prove it.

How is that? If he had 10 rows of 10 sheaves - if he began gathering from north to south and forgot a sheaf in the middle of the row, it is not Shichechah, because we can assume he intended to gather (afterwards) from east to west.

Question: If he then gathered from east to west and forgot that same sheaf, does it become Shichechah? (Note: The answer below was also given earlier in Perek 5 Halacha 2 - zevachim daf 49.)

Answer: (There are two versions of the ruling of a Baraisa) - If a person gathered (from a row of piles) the first pile, the second pile and the third pile, but forgot the fourth pile -

Version 1 - if he took the fifth pile, the fourth is Shichechah;

Version 2 - if he delayed enough time to take the fifth pile, the fourth is Shichechah.

(R. Bun bar Chiya resolves them): In Version 1, there is also a sixth pile (so that he took three piles and left three piles, and since there are three remaining, they can be considered a separate row). In Version 2, there is no sixth pile, so that only the fourth and fifth remain and they are still considered to be part of the first row - if he forgot the fourth, even before he took the fifth, it can be considered Shichechah.

Conclusion of proof: In Version 1, before he took the fifth pile, isn't the fourth pile already considered part of the separate row (containing the fourth, the fifth and the sixth, so that it was already saved from Shichechah) but you still say that it is Shichechah - here also, in your case, it should be Shichechah!

Question: If one sheaf was large (and there were two small sheaves next to it), if he gathered the outer half of the large sheaf, the inner half is viewed as part of a row (and is not Shichechah). But if he gathered the inner half, can the outer half be viewed as part of the row?

If he gathered the upper half, the lower half is viewed as part of the row. But if he gathered the lower half, can the upper half be viewed as part of the row? (The Gemara leaves these questions unanswered.)