Richard Sarason, "Toward a New Agendum for the Study of Rabbinic Midrashic Literature," Studies in Aggadah, Targum and Jewish Liturgy in Memory of Joseph Heinemann, ed. Jakob Petuchowski and Ezra Fleischer (Jerusalem, 1981) 66.
More fundamentally at issue here between Heinemann and myself is a historical model of the relationship between the rabbis and other Jews during this period. Heinemann's conception...might be characterized as volkisch: the rabbis are leaders of 'the people' and, in their midrashic activity, essentially popular preachers. I am more convinced by Neusner's model (in A History of the Jews in Babylonia) of a caste-like group that aspires to leadership, but is also preoccupied with its own internal 'Torah of being a rabbi', and with its own salvific rituals of study and ordering of the inherited rabbinic tradition. I suspect (although I cannot be certain) that this description would apply mutatis mutandis to the rabbinical group in contemporary Palestine as well. In this framework, rabbinic homilies in the documents before us could equally (or more) plausibly be construed as being primarily for internal rabbinic consumption and edification--particularly when the literary characteristics of the materials tend to support this construction...[I]t is interesting to note that the later homiletical midrashim, from the period of the Arab conquest (Pesiqta Rabbati and other Tanhuma-type compilations), contain considerably fewer attributions...I do not know how to interpret this fact, but it certainly reflects a shift of concerns on the part of the compilers of the documents.
For whom were the rabbinic midrashim in the Amoraic period (fifth-sixth century, maybe beyond)? Were they homilies delivered in synagogues? Or were they for the internal "consumption and edification" of the rabbinic academy? Rabbinic midrashim tend to be concerned about citing sources, of specifying which rabbi is making a particular point. Later homiletical midrashim, however, are not as preoccupied with this, and Dr. Sarason appears to conclude that the later midrashim were preached in the synagogues.
Dr. Sarason's perspective clarifies for me his position in his article, "The Petichtot in Leviticus Rabbah: 'Oral Homilies' or Redactional Constructions?" in the Journal of Jewish Studies 33 (1981). Dr. Sarason discusses the petichta. What's a "petichta"? The midrash cites a verse from the Pentateuch to expound, and it starts its exposition by referring to a verse that's not from the Pentateuch. This non-Pentateuchal verse is called the "petichta." Through the course of its exposition, the midrash tries to tie the petichta verse back to the verse from the Pentateuch. Midrashim can also have composite petichtot, in which there's a petichta verse, another verse cited, and an attempt to tie that other verse to the petichta verse. So a petichta can be inside of a petichta!
For Dr. Sarason (if I understand him correctly), many composite petichtot were originally independent units, but they were inserted into the midrash's discussion of the Pentateuchal passages. The aim was to make the midrash a repository of rabbinic thought. I wondered what the independent petichtot would be used for prior to their inclusion in the midrashic exposition. Sermons? I have a hard time with that, since (right now) my impression is that sermons were about Pentateuchal passages. A free-flowing exposition of a non-Pentateuchal passage wouldn't count as that! But maybe it was discussed within the academy, and, naturally, an academy would want to preserve that piece of rabbinic thought.
I've not read both sides, but I wonder if sermons before a congregation could also use composite petichtot, as a means to hold the congregants' attention and keep them wondering how the preacher will tie the verses together. Also, I wonder if Dr. Sarason believes there were sermons in the synagogues of the rabbinic period. I may ask him that the next time I meet with him.