Scattered about through the old shtetls of Europe were two kinds of rabbis. Some rabbis really knew how to learn. They were proficient in the intricacies of Talmudic dialogue and had accumulated substantial amounts of Talmudic learning. Others weren’t nearly as sophisticated. They merely managed to get by. They could understand the Talmudic material that they would read in a perfunctory manner; and they could then rehash it for the benefit of the listening public. But they did not innovate or show much in the way of erudition. Now both these types of rabbis held their regular discourses (known as drashos) at the appointed times throughout the year. Shabbos Hagadol was one such designated time, among several others.
It was customary for a rabbi to draw up a list of Sources Consulted, also known as Mareh Mekomos. It displayed the various sources that had been tapped in constructing the treatment of the topic that he (the rabbi) was to deliver. It would be hung up on the wall of the synagogue where everyone could see it – in advance of the actual giving of the discourse. People would consult these sources, so that they would be better prepared to follow the ins and outs of the rabbi’s sometimes mentally wrenching discursive dialogue. However, customs varied as to how much in advance of the discourse the Sources Consulted listing would actually be hung up.
In some towns, they would be hung up well in advance, perhaps as much as two weeks in advance of the drasha date. If, for example, it was a Shabbos Hagadol drasha, the listing might be hung up as early as on Rosh Chodesh Nissan! Typically, rabbis following this custom were from the first category: their learning ability was first rate. Their drashos were truly masterpieces of Talmudic erudition. Being well prepared for them was of the essence, if the people in attendance were to profit from their efforts in following and properly comprehending the flow of the exposition.
In other places, by contrast, the List of Sources would not be posted until the last moment – not much before the discourse was scheduled to be delivered. These were, characteristically, places whose rabbi fell into the second classification: they could scrape together a discourse but not show any profound insights or modes of entanglement. Posting Sources was, for them, merely a formality, and didn’t impact too much, one way or the other, on listeners’ ability to comprehend. Such rabbis might even feel threatened by the prospect of their listeners’ receiving a heads-up in regard to the anticipated content of their drasha.
In the Haggada of Passover we read: yachol merosh chodesh talmud lomar bayom hahu. I assume that the reader is familiar with the literal understanding of this passage. However, homiletically, it may be interpreted as an allusion to the state of affairs just discussed: Yachol, meaning if the rabbi is really capable (he is accomplished and has a great deal of learning capacity), then merosh chodesh, meaning that he will have posted his list of Sources Consulted (as early as) on Rosh Chodesh. However, if talmud lomar, meaning he is merely capable of rehashing Talmudic material that he has come across, then bayom hahu, meaning that he will likely wait until the very day of his drasha before hanging up a list of his Consulted Sources. He is in no hurry.