Normal Way of Carrying

Abaye sat and related the above halachah. Rav Ada bar Masnah asked him from the following braisa: [There is a halachah of kim leih bid’rabbah minei -whenever someone is deserving of two punishments, he receives the one which is more severe.] If one steals a purse on Shabbos, he is obligated to pay for the purse as well, as he had already stolen before he had been liable to be stoned (for desecrating Shabbos). If he was dragging the purse little by little out of the original owner’s domain, he is exempt from paying for the purse, as the act of desecrating Shabbos and the act of stealing happened at the same time. Now, a purse is something that is normal to be lifted, and nevertheless, it is acquired through meshichah!?

Abaye answered: It is referring to a purse that is tied by a string.

Rav Ada (thinking that Abaye meant that it was small) asked him back: I also understood it to be referring to a small purse (and that is why I asked my question that it should not be acquired through meshichah; rather, through hagba’ah)!?

Abaye responded: It is referring to a purse that needs a string attached to it (due to its large size, it can only be dragged; not lifted).

Tosfos asks: How could the Gemora think that the braisa is referring to a small purse which can be lifted? If so, he should not be liable for violating the Shabbos, since it is not the normal way of carrying something!?

Tosfos answers that although with respect to acquisitions, the item can only be acquired through lifting, for this is its normal mode of transport; nevertheless, with respect to Shabbos, it is regarded as normal.