The second chapter of Massekhet Eiruvin opens with a discussion of the unique case of a water hole in the public thoroughfare that is surrounded by four right-angled walls in each corner – referred to by the Mishna as Deyomadin – in order to allow access to the water for travelers and their cattle.
The Gemara then searches for the etymology of the word Deyomadin:
The Gemara asks: What are deyomadin? Rabbi Yirmeya ben Elazar said: Two [deyo] posts [amudin], which are put together to create a single corner piece. Rabbi Yirmeya ben Elazar suggests that it is from the Greek word “duo”, and that the word is “duo-amudim” – double standing walls.
This leads the Gemara to offer a list of expressions that are based on the concept of duo. For example, Rabbi Yirmeya ben Elazar suggests, based on the passage in Tehillim 139:5 – Ahor Va-kedem Tzartani (“you have formed me behind and before”) – that God’s original creation of man was deyo-partzuf – double faced. This fits in with one of the explanations of the creation of man (in Bereshit 2:23), on which there is a disagreement between Rav and Shmuel.
One said: It means a female face, from which God created Eve; and one said: Adam was created with a tail [zanav], which God removed from him and from which He created Eve.
The passage in Bereshit indicates that Eve was created from Adam’s tzelah. Although the word tzelah is usually translated as “rib,” the amoraim argue as to whether it means “face,” in agreement with Rabbi Yirmeya ben Elazar’s explanation, or if it means zanav.
The Aruk explains that the word zanav in this context, as well as in many other places in the Talmud, means something that is extraneous and does not fit properly – something that looks unusual in appearance or size. According to the Rashba the zanav is something secondary, as the importance of the tail in comparison with the head.
According to the opinion that Eve was created from the zanav, we need to understand the passage in Tehillim which seems to say that man was created “behind and before.” Rav Ami interprets the idea of “behind” in the passage as being at the end of the act of creation, and “before” means that he was first for punishment (the Flood).
The Ritva explains that Rav Ami understands that the root of the word tzartani in the passage in Tehillim is not yatzar – “creation,” rather it is tzarah -“catastrophe.” Thus, the passage means “after creation, but before the disaster.”