Gittin 21 - What to write the Get on?
Can one write a Get on a big leaf growing on a tree, then tear it off and give it to his wife? - No! Since the Torah said, " And he will write for her a letter of divorce and give it ," we understand that he must be able to give the Get immediately after writing. Here we have another action, tearing off, intervene between writing the Get and giving it, and therefore such Get is invalid. If he did, however, write on a leaf, tore it off and gave it to his wife, he did not do things correctly, but the divorce is valid.
The last rule is in direct contradiction with the previous one! We just finished explaining why the Get is invalid, using the "He will write and give" - in one breath - and now we are saying that it is valid after all!?
The answer is that there are two parts in the Get. The first one is the "active," or "explicit" part, which effects the divorce. It gives the names of the husband and wife, the place and the date. It also contains the key phrase "you are free to marry anyone". This "active" part was initially left out on the leaf, and only the secondary part was there. The active part was written in after the leaf was detached, so the Get was really written correctly.
The explanation above may sound forced. Another explanation is that we are dealing with the opinion of Rabbi Meir that writing does not matter, only signing by the witnesses does, and it accomplishes the divorce. And they signed after the leaf was torn off the tree. This sounds more natural, why did they give the first explanation at all? - Because of the rule that in divorces the law follow Rabbi Elazar, not Rabbi Meir, so they did not want to ascribe this rule to him.
Art: Walnut Tree in a Thomery Field by Alfred Sisley