In the last lesson he ever gave (on the last Rosh Hashana of his life-18 days before he left this world), Rabeinu teaches us that not all people are fitting to give rebuke, as is brought down in Masechet Arachin 16b. Rabeinu explains that if Rabbi Akiva said he was doubtful that there was someone in the generation worthy of giving rebuke, all the more so with regard to our generation.
Rabeinu adds that one who is unworthy and still rebukes others causes tremendous damage to the soul of the one being rebuked and the upper worlds which are dependent upon this this soul. On the other hand, one who is fitting to give rebuke - one who’s voice is in the aspect of the voice that waters the Garden of Eden- adds and instills a beautiful fragrance within the soul of the one being rebuked.
Rabeinu discusses how this voice is connected to the melody that will burst forth in the future (Tikkunei Zohar Tikkun 21) (Na Nach Nachma Nachman Meuman) at the time when G-d will renew the world.
Rabeinu also discusses that prayer is necessary to attain this voice and that prayer requires compassion and specifically Da’at. Rabeinu also explains how if Da’at is blemished, it’s impossible to pray in the aspect of mercy and entreaties. Tefilla is brought into the aspect of Din/judgement, sexual immorality increases in the world, and now the evil side can swallow our prayers…
Therefore, we need a master of great strength who knows how to pray in the aspect of judgement. This prayer stands in the throat of the Satan and makes him spit out all the prayers, holiness, compassion, and mercy he swallowed previously!
Rabeinu also discusses the subjects of thunder, converts, the revelation of glory, the spread of prophecy, healing, forgiveness, when Jewish souls come together/the idea of Batim-houses, the Tzadik, refining the strength of the imagination, holy faith, searching for a true leader and attaching yourself to him, the renewal of the world, Divine Providence, nullifying nature, the Land of Israel, the Shofar, the lungs, and many other lofty concepts!