Kelim, Chapter Twenty-Five, Mishnah Three
1) Measures of wine or oil, a fork-ladle, a mustard-strainer and a wine-filter have an outer and inner side, the words of Rabbi Meir.
2) Rabbi Judah says: they do not have.
3) Rabbi Shimon says: they do have, for if their outer parts contracted uncleanness that which is inside remains clean, and immersion is required.
Section one: A “fork-ladle” is an instrument with a ladle on one end and a fork on the other end. According to Rabbi Meir, all of these vessels have inner and outer sides, so if an impure liquid touches them on the outer side, the inner side remains pure.
Section two: Rabbi Judah disagrees and holds that they do not have inner and outer sides. No matter where the liquid touches, the entire vessel is impure.
Section three: Rabbi Shimon seems to bridge between these two opinions. These vessels do, in some sense, have inner and outer sides, and if an impure liquid comes into contact with the outer side, the content on the inside remains clean. However, the entire vessel requires immersion in order to purify it, even the inside of the vessel. In other words, the paradox isthe inside of the vessel requires immersion, but the contents are clean.