daf bit: Yoma 13

As we learned in the mishna that begins this tractate, a week before Yom Kippur a backup high priest is prepared, just in case something happens to the high priest that disqualifies him from performing the service. The g'mara discusses the case of temporary disqualification: suppose an accident befalls the high priest and the substitute takes over, and then the original high priest recovers -- does he resume his duties, and if so what happens to the substitute? R. Meir says the original one returns to duty and the substitute remains bound by the obligations of the office. R. Yose, however, says that the original one returns to duty and the substitute cannot be either high priest or a common priest -- he can't be high priest because it would cause ill feeling, and he can't be a common priest because we can promote in sanctity but not downgrade. (Having held the higher office, he can't "move down" -- but he can be removed entirely.) The g'mara records that the halacha is in accord with R. Yose, with two qualifications: if the substitute ignores the result and performs priestly service anyway it is valid, and if the high priest later dies the substitute returns to service. (12b-13a)

Aside: the "don't diminish in sanctity" factor also figured into the talmudic story of how R. Elazar became head of the Sanhedrin, kind of.

No answer yet on the question from last week's daf bit about the substitute wife, by the way.