I can’t do without you, I’m not always fit to be your teacher,
Sometimes my wings are crushed,
My spirit broken,
But if you seek me out,
And if you search my Torah,
Together we can open a book and learn.
Parshat Ekev, August 16, 1941
It appears that the meaning of the Talmud quoted above is this: Even when a teacher does not always resemble an angel, but only does so from time to time we should still seek Torah from his mouth even during those times he does not resemble an angel. If, however, he never resembles an angel we should not learn Torah from him. Why is it that even if the teacher only rarely resembles an angel, his students should ask him to teach them Torah? Why must they request Torah from him at those times?
They need to request the Torah from him then, because when the teacher does resemble an angel, he is already a messenger of God and students do not need to ask anything of him; as an angel, his job is to teach them Torah. However, when he does not resemble an angel, then his students have to ask him for Torah so that the level of angel, which is dormant in the teacher, will reveal itself. If the students do not ask the teacher for Torah then the teacher suffers damage, because he is not aroused to teach. In addition, it is even possible for the degree of angel in the teacher to be dulled, and to disintegrate. This is what the verse (Psalm 12:2) quoted above means when it says, "The pious have ceased to be; the believers have disappeared from among the children of men.
ומשמע מזה שאפילו אין הרב דומה תמיד רק לפעמים דומה למלאך ד',
כבר יבקשו תורה מפיהו, ובאם אין לו שום זמן אשר יהיה דומה למלאך לא
יבקשו, אבל אם ישנם זמנים אפילו רק לפעמים שדומה למלאך ד', אז גם
בשעה שאינו דומה, כבר יכולים תלמידיו לבקש תורה מפיהו, והם יבקשו ממנו.
כי בשעה שדומה למלאך אז הוא שליח מד' ואינם צריכים לבקש, כי הוא
בעצמו אומר להם תורה, אך בשעה שאינו דומה למלאך, הם יבקשו תורה
מפיהו והם יעוררו בו שבחינת המלאך ד' צבאות שבו תתגלה בו, אבל אם
אין תלמידיו מבקשים גם הרב נפגם ולא מתעורר, ויש שגם יכהה וידעך חלק
המלאך אשר בקרבו כנזכר לעיל שלכן "גמר חסיד" מפני ש"פסו אמונים מבני
אדם".