Our Gemara on Amud Aleph records an interesting idiom used by Rav Huna in response to a question he did not want to answer. He told the person, “Look, a raven flies in the sky.” Rashi tells us that it was meant to distract the petitioner, presumably in the hopes that he would leave him alone as he was exhausted at that time from giving shiur and Torah study. Rabbenu Chananel explains that it was actually a criticism, suggesting his question was foolish. In any case, it is an unusual phrase, and is there any more meaning to it than that?
This phrase comes up one more time in Shas (Chulin 124a), and that is in regard to Rav Huna’s son Rabbah, who used this same response when asked a question that he also apparently did not want to answer. This cannot be a coincidence. The Chida (Pesach Enayyim on Chulin) explains that indeed Rabbah used his father’s idiom. But, did it mean anything more? The Chida explains that every Torah question represents an occlusion in divine flow, instigated by the Sitera Achara (the other side, “Satan”), which is symbolized in the flight of a raven overhead, that is a temporary darkness. (Toras HaOlah III:21 says a similar idea.) Thus, Rav Huna and son were both making a double entendre. That is, aside from wanting to distract, they also were hinting that the question was troublesome and complex, and that they felt at least that time, unable to pierce the veil of darkness and confusion.
I will add my own two cents. Both questions asked in the Gemara involved liminal issues. Liminality is defined as the edge between two states. In our Gemara, it was a question about if an animal owned in partnership with a gentile can be slaughtered to eat on Yom Tov, since only half of it will be for the purpose of permitted food preparation. And, in Chulin it was a question about whether the flesh of bone marrow, which is not accessible from outside the bone, can accrete and be considered foodstuff to render it susceptible to impurity. In each of these questions, the answer will depend on whether two different items or states can be seen as joined or are still seen as separate. Thus, there is really a triple entendre here. The passing nature of the Raven which represents darkness and confusion also is a liminal state. It is neither here nor there, just as a halakhic question occupies this liminality, and in particular these halakhic questions which involve adjudicating a half-way state.
Confusion is a place of potentiality and unfulfilled promise and thus while it represents evil, is also the necessary evil. A world filled with light is essentially as sightless as a world filled with darkness because without contrast nothing can be seen. The potential to do evil, the so-called sitera achera, makes the choice to do good meaningful. Confusion and genuine uncertainty is a necessary state to arrive at clarity and learning.
Translations Courtesy of Sefaria, (except when, sometimes, I disagree with the translation .)