Gemara

40b (Mishnah): If one deposited a barrel with Shimon and designated where it should be kept, and Shimon picked it up for his needs, he is liable if it broke while he was holding it, but not if it broke after he put it down.

If the owner designated where to keep it, whether it broke while Shimon was holding it or after he put it down, he is liable.

(Beraisa - R. Yishmael): If one stole a lamb from a flock or a coin from a wallet, he returns it to where he stole it from;

R. Akiva says, he must inform the owner.

The Reisha of our Mishnah always exempts after he put it down. It is R. Yishmael, who allows returning theft without telling the owner, and all the more so, if he designated a place, for then he returned it to its place!

Question: The Seifa is like R. Akiva, who obligates telling the owner! All the more so, if he did not designate a place, he must inform him, for then we cannot say that he returned it to its place!

Answer #1: R. Yochanan said the Mishnah is not like one Tana.

Answer #2 (R. Yakov bar Aba): The case is, Shimon picked it up to steal it. (In Answers 2,3 and 4, the entire Mishnah is R. Yishmael. In the Seifa, he did not put it down in the designated place.)

Answer #3 (R. Noson bar Aba): The case is, Shimon picked it up to be Shole'ach Yad (to take some for himself).

R. Yakov and R. Noson argue about whether Shlichus Yad requires Chisaron (it applies only if the deposit was diminished).

Objection (and Answer #4 - Rav Sheshes): The Mishnah does not say that he took it (for himself), rather he moved it! Rather, Shimon moved it (to use it like a ladder) in order to bring chicks (from a high nest).

Rav Sheshes holds that Sho'el she'Lo mi'Da'as (one who borrows without permission) is considered a thief. R. Yochanan did not answer this way, for 'put it down' connotes in its place.

(Beraisa): If a shepherd abandoned the flock, and a wolf killed some of the flock, he is exempt. If he had left his staff on the killed animal, he is liable.

Question: Even if the animal was killed when the staff was still on it (so he did not return it after being Shole'ach Yad), he never did Meshichah (taking to one's premises. If, so Shlichus Yad does not apply!)

Answer (Rav): Hikishah (he hit it) with his staff and it ran in front of him. (This is Meshichah).

Inference: Rav holds that Shlichus Yad does not require Chisaron.

Rejection: Rav said that Hichchishah (he weakened it) with his staff. This is Shlichus Yad only because there is Chisaron!

Support: He hit it with a staff connotes that it was a harsh blow.

Rishonim

Rif and Rosh (3:20): Shlichus Yad does not require Chisaron, for Rava says so, and he is Basra.

Rosh: Once he picked up the deposit to be Shole'ach Yad and cause a loss, it is in his Reshus to be liable for Ones.

Rambam (Hilchos Gezeilah 3:11): If one intended to be Shole'ach Yad in a deposit, he is not liable until he did so. Once he was Shole'ach Yad he is liable, even though he did not diminish it at all, rather, he took it from one place to another in his Reshus in order to be Shole'ach Yad.

Rashi (41a DH v'Ha): What was the proof that Rav holds that Shlichus Yad does not require Chisaron? Perhaps he is a Sho'el she'Lo mi'Da'as! Sho'el she'Lo mi'Da'as does not apply to animals, for they normally weaken.

Question (Maharam): This is no reason to be more lenient according to the opinion that Shlichus Yad requires Chisaron!

Answer #1 (Ba'al ha'Ma'or): Indeed, we derived that Rav holds that Sho'el she'Lo mi'Da'as is a thief even without Chisaron, and likewise Shlichus Yad does not require Chisaron.

Rebuttal (and Answer #2 - Milchamos Hash-m): We cannot learn from one to another. Even the opinion that Shlichus Yad requires Chisaron agrees that Sho'el she'Lo mi'Da'as does not require Chisaron. (Shlichus Yad is more stringent, for it obligates even after he returned it.) Rather, Sho'el she'Lo mi'Da'as is only if he intended to remove it from the owner's Reshus. Shlichus Yad is even without such intent.

Defense (Gra CM 292:2): It is difficult to say that it depends on intent to remove it from the owner's Reshus. Rather, a Shole'ach Yad is surely Sho'el she'Lo mi'Da'as. For a deposit, this is Shlichus Yad. R. Yakov holds that Shlichus Yad requires Chisaron, and all the more so Sho'el she'Lo mi'Da'as does. R. Noson holds that Shlichus Yad does not require Chisaron, but Sho'el she'Lo mi'Da'as does. Rav Sheshes holds that Sho'el she'Lo mi'Da'as does not require Chisaron if he does not intend to cause Chisaron, and all the more so Shole'ach Yad, who intended to cause Chisaron, applies even without Chisaron.

Nimukei Yosef (23a DH Masnisin (2)): A Shomer becomes liable in three ways. (1) He lifted it with intent to steal it, or (2) even to cause a loss and take a little. This is Shlichus Yad, even if it broke before he took. (3) If he lifted it with intent to use it, he is a thief even before he used it. This is called Sho'el she'Lo mi'Da'as. Normally, a borrower is liable because he gets all the benefit. Here, the owner benefits, for he wanted it to be in the Shomer's house! We hold like R. Akiva, that once he used it in a way that the owner objects to, he ceases to be a Shomer, and the owner has no benefit.

Poskim

Shulchan Aruch (CM 292:1): If a Shomer lifted the deposit for a use that causes no loss, he is not liable until he uses it. He is not liable for Shlichus Yad, since he does not diminish it. Rather, he is a Sho'el she'Lo mi'Da'as, which is like a thief.

Gra (2): This entire Sa'if is from the Tur. We do not find that Rashi, Tosfos or any Poskim hold that Shlichus Yad applies without intent to take (and cause a loss). The opinion that Shlichus Yad does not require Chisaron requires that he intended to cause a loss. The Ra'avad holds that Shlichus Yad is only if he intended to take the entire deposit. Rashi asked how we learned about Shlichus Yad from the shepherd. Perhaps he is a Sho'el she'Lo mi'Da'as! The Tur answered that a borrower is only after he used it; Shlichus Yad applies to animals even before using them. We must say like Rashi, that if the labor will cause a loss, he is Shole'ach Yad, and if it will not cause a loss, he is a borrower. Both of these are even before using it.

Shitah Mekubetzes (41a DH Tirgema, citing the Ritva): Any person can be a thief or Sho'el she'Lo mi'Da'as, but Shlichus Yad applies only to a Shomer. All of these are only after Meshichah. Without Meshichah, it is in the owner's Reshus. If one took with intent to steal part or whole or cause a loss and not pay, he is liable for Ones even before causing a loss. A Shole'ach Yad intends to cause a loss and pay for it. If something is normally rented, a Sho'el she'Lo mi'Da'as intends to pay the rental, but the owner could lose from his usage. If no loss can occur, no one would consider Sho'el she'Lo mi'Da'as to be a thief. This is like Rashi, the Ramban, Tosfos and the Rashba, unlike the Ba'al ha'Ma'or.

Ketzos ha'Choshen (2): According to this, if the owner left it in front of David and David did not accept Shemirah, he cannot become Shole'ach Yad. If he intends to pay, he is exempt for Ones. The Rambam and Shulchan Aruch (Sa'if 2) obligate swearing that he was not Shole'ach Yad. This refers to what applies even not to a Shomer (theft and Sho'el she'Lo mi'Da'as). The Chidush that one is liable through a Shali'ach applies only to true Shlichus Yad of a Shomer.

Gilyon Maharsha (359:2 DH Afilu): Even though one may not steal with intent to pay, the Shitah holds that he is not liable for Ones like a thief. The Rashba holds that a Shomer who gave to a Shomer is a thief, even though he intends to return it. It seems that the Rambam agrees. It seems that Tosfos (36a DH Ein) exempts from Ones (according to the Halachah) one who gave to a Cheresh, lunatic or minor. This is like the Shitah. Tosfos (30a DH l'Tzorcho) holds that one is not a thief if the item cannot be harmed.

Rema: If he returned it to the place from where he took it, he resumes his law of a Shomer, since he was a mere borrower.

Shulchan Aruch (6): If one deposited a barrel with Shimon, whether or not he designated a place for it, and Shimon moved it for his own use and it broke, he is liable, whether it broke before or after he returned it to its place.

Rema: If he moved it for the need of its place he is liable for negligence and exempt for Ones. If the Ones was due to the change of place, he is liable before putting it down. If the owner designated a place, he is liable even after he put it down.

Gra (16): He is exempt for Ones, for Shlichus Yad and even Sho'el she'Lo mi'Da'as is only when he intended to use the deposit itself.