Although we have learned that if someone attempts to make a sanctified animal temurah – he tries to exchange it with another animal – he will end up transgressing a commandment and that both animals will become sanctified, nevertheless there are situations where such an exchange will be successful. If a sanctified animal develops a permanent blemish that will disqualify it from being sacrificed on the altar, such an animal must be redeemed and a replacement purchased with that money. According to the Mishnah on yesterday’s daf (=page), if such an animal were exchanged for an animal that is fit to be sacrificed, the exchange would work, although it would be necessary to make up the value of the original animal in the event that it is worth more than the replacement.
On today’s daf, Rabbi Yohanan teaches that on a Torah level, the exchange is valid, and it is the Sages who added the requirement to make up the value of the original animal in the event that it is worth more than the replacement. Resh Lakish argues that making up the value of the animal is also a Biblical requirement.
One of the explanations for this difference of opinion is whether the teaching of Shmu’el is accepted, for Shmu’el is quoted as teaching that if a sanctified object worth a maneh was redeemed on a perutah, it is a valid act. (A perutah is the smallest coin that was in use in the time of the Mishnah; a single dinar contained 192 perutot, and a maneh contained 100dinarim.)
Shmu’el’s teaching certainly explains Rabbi Yohanan’s ruling. In his Emet L’Yaakov, Rabbi Yaakov Kaminetsky suggests that if Resh Lakish agrees with Shmu’el he can explain that there are two separate elements to a sanctified object. Aside from the holiness, a consecrated animal is also the communal property of the Jewish people. Even if its holiness can be removed by means of this exchange, the full value must be paid to ensure that full compensation is made.