Mishnah 62 is a remarkable mishnah, built on the one before it. We have already learned the rule: someone who eats Terumah unintentionally must pay the principal - he takes ordinary food that has already been tithed properly and gives it to a kohen, and it becomes new Terumah by Torah law. Beyond that, a separate additional payment of a chomesh is imposed on him, that is, an added fifth, which amounts to a quarter (25%) of the amount he ate. Someone who unintentionally ate four grapes of Terumah returns four grapes as the principal and adds a fifth grape as the chomesh.
Two aspects of the payment of the principal:
Compensation for a monetary loss: just as someone who enters his friend's house and eats his food must compensate him and provide a replacement for what he ate.
Preserving the sanctity: a kind of conservation law of sanctity - he must create new Terumah, since the world is, as it were, missing the Terumah that was in it beforehand.
For this reason the payment is not made in money but in food: ordinary grapes from which all the tithes have been separated, fit to be made into Terumah anew. In this way the world loses no Terumah, and the Terumah of the chomesh is even added to it.
To whom are these payments made? To the kohanim. And here the mishnah discusses a fascinating case: a person who ate Terumah at a time when it was not permitted to him - unintentionally and in the normal manner of eating, and therefore became liable for the principal and the chomesh - and afterward became fit to eat Terumah. To whom must he pay?
The case is that of a woman. A woman born to a father who is not a kohen is a bas Yisrael; she is not a kohenes, and her status is like anyone who is not a kohen - she is forbidden to eat Terumah, and if she ate it she is liable for the principal and the chomesh. But a bas Yisrael who marries a kohen becomes part of his household, and she is therefore entitled to eat Terumah.
This law is derived from the verse in Bamidbar (18:11), that all the pure ones in your house may eat the Terumah - and the verse comes to include even the wife, for although she is not of the seed of kohanim, she is now one of the members of the household. Other members of the household as well, including purchased slaves and animals, eat Terumah as it applies to them, and this is derived from another verse elsewhere.
And now for the case before us: a bas Yisrael ate Terumah unlawfully and became liable for the principal and the chomesh, and afterward married a kohen, so that from now on she is permitted to eat Terumah. To whom must she pay the principal and the chomesh?
The law depends on the ownership of the Terumah that was eaten:
Terumah to which no particular kohen had acquired rights: Terumah that was designated to be given to any kohen, and no kohen had taken a private right in that portion - now that she has become the wife of a kohen, she herself is a fit recipient, and she can give the payment to herself.
Terumah belonging to a particular kohen: here it is not only a question of restoring Terumah to the world, but of having eaten something that was not hers, and she must pay compensation to its owner.
In the first case she may pay herself both the principal - the four grapes she ate - and the chomesh, the fifth grape, and eat those five grapes. However, she must take five grapes, declare them Terumah, and give them to herself as compensation. This law reflects exactly the principle presented above: she must restore the quantity of Terumah in the world and even add to it. It is not enough for her to say, "I will take this for myself and balance the account to zero" - she is required to raise those five grapes to the status of Terumah, and only then eat them herself.
In the second case, where the Terumah she ate before her marriage belonged to a particular kohen, she is like a thief, who caused a loss to the kohen and ate his food. Therefore she must return the four grapes to that kohen in whose possession they had been, since this is his property - and the same would apply had she eaten ordinary unconsecrated food of his, in which case she would have to compensate him for his loss. But the addition, that fifth grape which comes to effect atonement for her, she may give to herself, since she is the wife of a kohen, and eat it herself.
And in the words of Chazal, language that may well predate even the arrangement and writing down of the Mishnayos:
"HaOchel Terumah shogeg" - one who eats Terumah unintentionally: eating specifically, to exclude destroying it; and unintentionally specifically, to exclude one who does so deliberately. And Terumah here includes all four of its types: Terumah gedolah, terumas maaser, challah and bikkurim.
"meshalem keren labe'alim" - the principal amount of what was lost is paid to the original owners, if there were such owners. And again, the payment is made with tikkun chullin - ordinary produce from which the tithes have been taken, which is then elevated to become Terumah by Torah law.
"vechomesh lechol mi sheyirtzeh" - the additional fifth need not be given to the particular owner of the Terumah that was eaten, but rather to any kohen the one who ate it wishes. And in our case, once the woman who ate it became the wife of a kohen, she herself is a legitimate recipient, and she may give the fifth to herself or to any other kohen she wishes.
In summary: We have learned that the payment of the principal and the fifth is meant both to compensate for the loss and to restore the Terumah in the world and add to it, and therefore it is made with food and not with money. A bas Yisrael who ate Terumah unintentionally and afterward married a kohen: if she ate Terumah to which no particular kohen had acquired rights, she pays the principal and the fifth to herself, provided that she elevates the produce to the status of Terumah; and if she ate the Terumah of a particular kohen, she returns the principal to him, while the fifth goes "lechol mi sheyirtzeh" - to whomever she wishes, even to herself.