Our Gemara on Amud Aleph quotes the scriptural source for the chalifin acquisition, whereby transfer of possession is confirmed via exchange of an object, also known as kinyan sudar. In Megillas Rus, Boaz acquires the rights to the field from Plony Almoni and also presumably secures his agreement that he will marry Elimelech’s (their relative) former daughter-in-law, Rus (Rus 4:7):

Now this was an ancient custom done in Israel in cases of redemption or exchange: to validate any matter, one man would take off his sandal and hand it to the other. Such was the practice in Israel. 

The literal word used for the sandal in the verse is na’alo which comes from the root N-A-L enclosure. It connotes an article of clothing that wraps tightly around the skin, such as a sandal though Rav Yosef Bechor Shor also says it can be a glove (see his commentary on Shemos 3:5). There are three instances in the Torah where this na’al (sandal enclosure) is mentioned. The first is what we saw above by Boaz, and the second instance is when Moshe was instructed to remove his sandals by the burning bush (Shemos 3:5). The third reference is by the chalitza ritual of the Levirate marriage (Devarim 25:10). The fact that this acquisition method uses, at least in the scriptural examples, an item of clothing that wraps around the skin, and a shoe of sorts, indicates a process that has great significance to the Zohar (Chukas 180a).

The words “ancient tradition” and “to validate any matter” used in Megillas Rus are taken literally by the Zohar. The verse by Boaz is then read as follows: “And this ancient tradition is to enact any matter; One must remove his coverings...” This process, of removing his coverings, is not just clothes. It is a transfer and change in self-manifestation, that is also a heavenly reordering that approves of the transaction. It is literally a divestment (di-vest = des vesture in Latin, removing garments.) In mysticism and Jungian psychology, clothes represent a persona, a manifestation of self. Thus, Moshe had to shed certain physical garments and shift an aspect of self in order to encounter God on a new prophetic level. So too, the man who refuses to marry his deceased and childless brother’s wife, is divesting himself of his brother’s ghost or persona. The shoe represents agency as our feet carry us places, and also represents descendants (see for example Eiruvin 70b, that “heirs are the father’s foot”.)  So the foot (descendants) are divested from the brother. 

Similarly, when an object is given to another, there needs to be a heavenly sanction to allow the possession to transfer. This mystical idea also can explain the opinion of the Amora, Levi, who holds that the chalifin acquisition is accomplished via the giving over of the original owner’s vessel. Rav holds that the one who is acquiring GIVES a vessel to the original owner, and this signifies and effectuates the owner exchanging and transferring the desired item to the buyer or possessor. This is easy to understand because it symbolically is a trade. But how do we make sense of Levi’s opinion? Why would transferring one object cause another to transfer as well? But now can explain it as a sort of prayer or acknowledgment that the transaction is sanctioned by God. This is similar to the signs of sweetness or successful year which we enacted on Rosh Hashana by eating certain foods that have symbolic positive connotations (Kerisus, 6a.) 

A person’s possession is not merely a thing, it is a means by which the world and he interact. Our possessions have an impact on us. One might wonder, do we own our possessions or do they, in fact, own us? To the person who lives a spiritual life, nothing is lacking in sacred potential. When we buy or sell, divest or acquire, we humbly pray that God guide our experiences and allow us to use them as tools and means for elevation. This is similar to the following sentiment expressed in Berachos (35a), as to why one must recite a blessing prior to benefiting from the world’s pleasures:

It is written: “The earth and all it contains is the Lord’s,” and it is written elsewhere: “The heavens are the Lord’s and the earth He has given over to mankind” (Psalms 115:16). There is clearly a contradiction with regard to whom the earth belongs. The answer is that the verse that says that the earth is the Lord’s refers to the situation before a blessing is recited, and the verse that acknowledges that God gave the earth to Man, is after the blessing. 

We recognize that there is no possession that does not belong to God, and by that recognition, we obtain permission to use HIs world. So too, the original owner humbly asks God to approve of and ratify this transfer, by enacting a symbolic transfer via the chalifin.