Menachot 24 - Two Flour Offerings In One Vessel

When Rav Kahana came to Israel, he met the sons of Rabbi Chiya who were pondering the following question: If one put two halves of his flour offering in a vessel so that they do not touch, and then a spiritually impure person touched one of the halves, does this make the other half impure? The rule is that a vessel combines the parts, but is it true even for impurity? Rav Kahana gave an answer from the wording of the rule, which does not state that it joins the halves, but only that it combines. This means that they are not joined for impurity.

If a zav (one with strong impurity) was lying on a sheet, the sheet acquired his strong impurity. If the owner then made this sheet into a curtain, on which no one can lie, then the previous strong impurity leaves, but since the sheet touches itself (every thread in it touches another thread), then it has the lighter impurity of being touched by a zav. However, Rabbi Yose asked, "Which zav touched it?" - Rabbi Yose means that a thread touching another thread means nothing, because this is hidden impurity, which does not count.

Art: Rembrandt Van Rijn - The Holy Family with a Curtain