Pesachim 18 - Who contaminates whom
To add further shades to the question of ritual purity, the Talmud considers a situation where the liquid might have touched something else, but it might not. On this there are three opinions.
Rabbi Meir says that the power of liquids to make other objects impure is only decreed by the Sages, and they never went as far as to forbid things out of doubt. Therefore, the object is pure. Rabbi Yehudah says that it is the Torah who gave the liquid the power to transmit impurity, and to avoid any doubt in this, we must consider the objects impure. Finally, Rabbi Yose and Rabbi Shimon divide this even further. If it was food that was possibly touched by the liquid, then - since this situation is given by the Torah - we must consider food impure. However, if it is a vessel, then - since this impurity would be only decreed by the Sages - we must consider the vessel pure.
They derive their opinions from the word "yitma" used by the Torah, which means "It will become impure." Since this word can also be read "yitama", which would mean that it will make other object impure, here we begin to consider exactly which other objects will become impure.
Art: A personification of Purity by Simone Pignone