On two of the Temple practices - specifically, how the congregation would daven or meditate on verses while the kohanim were blessing the people. Plus, how "amen" was not said in the Beit HaMikdash, and what was said instead (and when). [Who's Who: Rabbi Abbahu] Also, the blessings by the kohen gadol on Yom Kippur, plus the ceremony of him reading passages from the Torah as well.