Kiddushin 26 - Methods of Acquisition
A large animal (cow or horse) is acquired by handing over its reins, and a small animal (sheep) by drawing it near.
Rabbi Shimon says that only lifting the animal acquires it. Then how does Rabbi Shimon acquire elephants? By having them step on bundles of vines.
Real property may be acquired by means of money, a document, or a proprietary act such as locking the gate. Movable property may be acquired only by "drawing it near." To protect buyers, the Rabbis abrogated the power of money to acquire so that sellers would guard the sold goods after receiving the money.