It's a Mishna - Huriot 3:8
>In the times of the Beit HaMikdash, the Kohanim had a large sacerdotal
>function (i.e. they ran the avodah [service] and performed the sacrifices)
>with the assistance of the Levites. What limited role that Kohanim have in
>the synagogue today (1st aliyah, the Aharonic blessing) is an artifact of
>that earlier role.
I don't think 'artifact' is accurate.
The Sefer Hachinuch (a list of the 613 commandments) says in Mitzva 378 -
Cohanim are commanded to bless the Jews daily.
This commandment is done in all communities in the Land of Israel,
and in Sephardic communities in Galut (diaspora).
The Ramah in OH 128:44 says Ashkenazim do it only when they are
'really' happy - Yom Tov (holidays) in the morning right before leaving
shul - so Ashkenazim in Galut only do it Yom Tov by Mussaf.
> What limited role that Kohanim have ...
I quote Sefer Hachinuch Mitzva 269 -
Jews are commanded to sanctify Cohanim even against their will!
He quotes Bavli Gittin 52b - 'Sanctify him' - for holy acts, put him
first.
He then quotes Midrash Sifra - 'Sanctify him' - against his will.
And he stresses - "This is all for HASHEM'S honor".
Personally, I have some pity on the Cohen.
I buried my mother z"l, he can't.
When I make a simcha (Bar mitzva, wedding, brit, etc.) most of the family
gets an aliya on Shabbat, he can only get a maximum of 3 aliyot.
In conclusion, we are born where Hashem sends us, and based
upon where Hashem sends us, Hashem decides what we can do,
what me must do, and what honor we get.
Hashem decides, not some men. And if Hashem wants someone to get
some honor, he/she gets it because Hashem says so, not because
he/she is honorable (e.g. parents/children, etc.)
IMHO, there is no such thing as "class distinction" in Judaism.
We are what we are because Hashem said so.
So lets be thankful that he made us what he made us.
Happy Chanuka.
Behatzlacha rabba,
Yisrael