What is "Musar"?
Malbim: The heart's nature is to picture the opposite of Chachmah, e.g. pride, envy, vengeance, cruelty - "Ki Yetzer Lev ha'Adam Ra mi'Ne'urav" (Bereishis 8:21). This causes the power of desire to fight with Chachmah. One's nature is to be drawn after desire, since he has no proofs for Chachmah. Chachmah's laws oppose the Nefesh's nature! Musar is needed to tie his Nefesh's powers, lest they slander laws of Chachmah and choose the path of folly. "Yir'as Hashem Musar Chachmah" (15:33). Fear planted in the heart has two branches. (a) Yir'as Hashem ties the powers of his Nefesh with ropes, lest they breach the law. When one believes in Hashem and knows that He gave the laws of Chachmah, he fears His honor, grandeur, judgment and punishment. He fears to veer from the laws of Chachmah that the exalted King commanded.
Why does it say "Lada'as Chachmah u'Musar"?
Rashi: These Meshalim were to inform people that they should toil in Torah, which is Chachmah, Musar and Binah.
R. Yonah #1: Chachmah is the Midah of Tzadikim, the ways of Emes and Tzedek that he will inform and explain in this Sefer. Musar is the detriment of Resha'im, and informing the damage and loss that comes from them. Many places in this Sefer, part of the verse discusses the Midah of the Tzadik, and part the detriment of the Midah of the Rasha. It is proper for one to chastise his Nefesh - first to distance from the Midah of the Rasha, and fence himself from it, lest the Yetzer ha'Ra make him stumble at times when it overpowers a person. Afterwards he should accustom his Nefesh to ascend in the attribute of the Tzadik's Midah. Not [everyone] who purifies from the Rasha's Midah rises to the Tzadik's level. They are at opposite extremes. One reaches the Tzadik's level only after toil and habituation.
R. Yonah #2: The good of man is to know Chachmah u'Musar. This is in place of a warning, like Zachor 1 .
Malbim: The Sefer's purpose is to know Chachmah [and Musar]. Chachmah is knowing all the Midos, ways and customs. In each, there are two opposite ways, e.g. cruelty and mercy, pride and humility, audacity and shame, eating and fasting, Kedushah and Tum'ah
R. Yonah: However, from what it says below "Yishma Chacham v'Yosif Lekach" (5), we learn that it speaks about the words of the Sefer, that he composed it to know from them Chachmah and Musar.
Malbim: According to this, one cannot be Yode'a Chachmah, for Yedi'ah is only something that one knows clearly, either via senses or axioms. Chachmah is only via tradition! However, via Meshalim, Shlomo taught Da'as of Chachmah. He explained the unknown via the known. Or, one can reach Da'as if he received Chachmah from one whom he trusts absolutely, as if he saw the matter himself.
What is "Lehavin Imrei Vinah"?
R. Yonah: Havanah of a matter is reaching the purpose of the one who said it, e.g. "Haven Lehalaz Es ha'Mar'eh" (Daniel 8:16), "Binu Na Zos Shochechei Eloka" (Tehilim 50:22). Sometimes it applies to recognition, e.g. "Avinah va'Banim" (below, 7:7), "va'Yaven Eli" (Shmuel I, 3:8). Imrei Vinah are deep matters that one cannot know until he contemplates them and thinks deeply to understand them.
Malbim: Lehavin is understanding a matter amidst another matter. It applies also to matters to which Emes and Sheker apply, and difficult expressions and hidden riddles that Ba'alei Tevunah say. Chachmah is gathered to the Nefesh from the outside; Binah comes from man's Nefesh and brings out explanations via comparisons of understanding.
