On 24b, the Gemara asks why a non-kohein is exempt for setting up the menora. The gemara answers that siddur haminora is followed by inserting the wicks, (and so is an avoda sheyeish achareha avoda). -So why is he exempt for setting up the wicks? -Because it is followed by pouring in the oil. -So why is he exempt for pouring in the oil? -Because it is followed lighting the minora. -So why is he exempt for lighting the menora? -Hadlaka is not an avoda. The Gemara's answer seems fraught with difficulty. If hadlaka is not an avoda, that means putting in the oil is NOT an "avoda sheyeish achareha AVODA", as the only procedure which follows it is hadlaka, and hadlaka is not an avoda! Thank you.
Shalom Spira, Montreal, Canada
When the Gemara says that one is not Chayav for doing an Avodah "which is followed by an Avodah," that "Avodah" is Lav Davka, and it refers to any act that must be performed following the Avodah being discussed. The proof is that the Gemara derives this principle (that one is Patur for doing an Avodah which has another labor after it) from the verse, "v'Avadetem," teaching that the Avodah must be one which "completes" (makes "Tam") the procedure and has nothing following it (even an act that is not performed by a Kohen but by a Yisrael, or one that occurs by itself -- see Tosfos Yeshanim 24b).
This might also answer a question which perplexed the Acharonim. Rashi (24a, DH Avodah Tamah) writes that one is Chayav only when one does an Avodah that is not followed by an Avodah, "but not when there is another Avodah after it, such as Shechitah, Kabalah, and Holachah, which have after it Zerikah." Why does Rashi mention Shechitah? Even if it did not have an Avodah after it, one would not be Chayav for doing Shechitah of the Korban, because Shechitah may be done by a non-Kohen (see Rashash)!
According to what we wrote above, the answer is that Rashi is explaining that the word "Avodah" in the Gemara does not refer only to the Avodah of a Kohen (although in order to be Chayav, it is obvious that a Yisrael is Chayav only when he does an Avodah that is exclusive to a Kohen). Similarly, Rabeinu Chananel (24b) writes the phrase " Melachah Tamah" and not "Avodah Tamah," to allude to this point.
Mordecai Kornfeld