There are four types among those who sit before the sages: the sponge, the funnel, the strainer and the sieve. The sponge absorbs all. The funnel takes in at one end and lets it out the other. The strainer rejects the wine and retains the sediment. The sieve rejects the coarse flour and retains the fine flour. (Avot 5:15)
Several commentators assert that this mishanh cannot be about types of memory since that was already the theme of Avot 5:12. Rather, the mishnah addresses discerning understanding. Some students lack the ability to distinguish among the various things they hear; they simply take everything in like a sponge. Others who resemble the funnel find it hard to retain anything. The third type of student resembles a strainer in that he makes poor judgments about which ideas to internalize, keeping sediment and releasing wine. Finally, the sieve shows discerning wisdom in only retaining fine flour.
R. Yisrael Lipschutz describes a student resembling the sponge in the context of a class given by a teacher. Apparently, he does not envision a student simply recording everything a rebbe says and filing it away in memory for eternity. Instead, the ideal students use their critical faculties to make qualitative distinctions among the ideas stated during the lectures. The best students combine independent thinking with reverence for excellent teachers.
What type of discerning evaluations does this mishnah refer to? Rambam, Rabbenu Yonah, and others write about differentiating between true and erroneous arguments. Indeed, people of wisdom know how to tell a false sevara from a sterling insight. They appreciate the difference between logic and falsehood and argue vociferously on behalf of the former.
In contrast, Meiri writes about distinguishing between ikkar and tafel, between the central ideas and the quaint side issues. This distinction proves more subtle and, perhaps, more significant. Two categories of correct ideas compete for out attention; there is no falsehood at work and yet we still require discerning wisdom. Some students become distracted by curiosities and sideshows. They want to know what kind of clothes we will wear in a resurrected state instead of investigating divine justice. Gematriot about Avraham interest them more than analyzing the life and activity of our first patriarch. They find lore about a golem or a dybbuk more interesting than the study of Tanach.
On the one hand, we may find it harder to reject these side points since a diligent student can marshal Torah sources addressing these issues. On the other hand, significant distraction from work that truly matters or the essential ideas of Judaism hinders Jewish education. The ability to make Meiri’s distinction may well be more significant than that of the other commentators since the trivial often looks more attractive than the false; therefore, it tempts more powerfully. The best sieves know how to exclude both the incorrect and the unimportant in the pursuit of fine flour.