Pirkei Avot - Ethics of the Fathers

~Level 1~
Tiferet Yisrael - here he is not referring to the levels of memory since that was taught earlier. Rather, he is referring to a sound or faulty intellect.

~Level 1~
Rabeinu Avraham Pritzel on Avot - this mishna is almost like the earlier mishna ("quick to hear.. etc."). Just that the earlier mishna was referring to understanding and receiving wisdom easily or with difficulty, forgetting or remembering. But this mishna revolves around a different matter. Namely, examining and discerning the truth from the falsehood in matters and to clarify and hold on to the good and drop the unsound and incorrect in the ways of pilpul (logical rigor). For the latter sometimes confuses from correct understanding.

~Level 2~
Bartenura - "four types among those who sit before the sages" - earlier regarding the characters of the students, he was speaking about the matter of memory and forgetfulness. Now he is referring to sound logic and discerning between what is correct and what is incorrect.

"the sponge" - he absorbs water, whether it is murky or clear. So too some have a broad heart and receive everything they hear but they lack the power to discern the truth from the falsehood.

"The funnel takes in from one end and lets out from the other" - a funnel is that which is placed on the opening of a barrel or jug when one wants to fill it with oil or wine. So too some [students] receive everything they learn but it leaves them just like it came.

"the strainer lets the wine run through and retains the pits" - he sifts out everything he heard in the Beit Midrash (study hall) and retains only the irrelevant matters.

"The sieve lets out the coarse flour and keeps the fine (choice) flour" - after sifting out the waste from the milled flour, the choice fine flour remains which is the important part.. So too there are some who have the power to clarify and elucidate what he heard and to extract the truth from the falsehood and the irrelevant.

~Level 3~
Matanat Avot - "four types among those who sit before the sages" - here the mishna is talking about a Rav who gives a shiur (class) in halacha or talmud in-depth. He presents at first one path built on a certain foundation and then afterwards brings questions and difficulties from here and there. He refutes this and answers that, bringing a proof from here or there and after an hour or more of warfare in torah, the Rav throws out the final resolution which explains the entire sugyah (topic) and all the problems are solved.

One of the students may tell himself: "why do I need to remember this entire path of the shiur and all its questions and pilpulim (rigorous logic)? Isn't it sufficient for me to know only the final conclusion from which the halacha is derived and that's it?"

On this the Tanna says to you: "no!". For in order to grow in torah and know how to mechadesh chidushim (deduce insights) in halacha, one must go through the entire long road of questions, refutations, answers, differences, etc. etc. and to get thoroughly entangled in this salad. In this way and only in this way does there come out in the end lamdanim gedolei torah (sharp torah scholars), as written in the talmud: "a person does not stand on words of torah unless he first stumbled in them" (Gitin 43a).

For it is not possible for each person to merely look a bit on the Gemorah (talmud) and then go straight away to a clear understanding of all the halachas and foundations in that sugya.

Rather, only he who toiled seriously to what the Gemorah wanted in the question and what it thought in the answer and what is the difference between the hav amina (assumption) and maskana (conclusion), etc.

Only such a person can merit in the end to illuminate all the foundations and boundaries in halacha that are in this sugya (topic).