Why is Torah so desired?
Radak: The wise and Yir'ei Hashem desire it (for they appreciate its attributes - refer to 19:11:2:2, 19:11:5:1).
Malbim: Torah also has the perfections that people pursue. It has benefit - it is more than desired than much gold and Paz. It helps [also for] civil life and success in this world. It has pleasure - it is sweeter than honey!
What is "Paz"?
Radak: Paz is good, clean gold.
Radak citing Ibn Ezra: Gems, that a person desires. The wise have a greater desire for Torah and Chachmah - "v'Chol Chafatzecha Lo Yishvu Vah" (Mishlei 3:15). Money is only in this world; Chachmah is in this world and the world to come. Money can be stolen, or last at sea or on the land. Chachmah is never stolen; one who has it does not lose it 1 . If one buys with money, or does business with it, he does not keep what he gave. If one teaches Chachmah, he does not lose, rather, he increases Chachmah!
Megilah 18b: "If you close your eyes on it (Torah), it is gone". Rashi - it is forgotten in the time of an eye's blink. (Perhaps Radak discusses one who is careful to constantly review his learning. - PF)
What is "Rav"?
Radak #1: It is like "Al Kol Rav Beiso" (Esther 1:8) - great in importance and grandeur (very esteemed gold).
Radak #2: It refers to a great quantity [of gold and Paz].
What is "Nofes Tzufim"?
Rashi: It is the sweetness of honey.
Rashi citing Menachem: Nofes is an expression of a drop - "Nofes Titofnah", "Nafti Mishkavi" (Mishlei 5:3, 7:17)
Why is Torah sweeter than honey?
Radak: Honey is the tastiest food, but if he eats too much, it harms him and he vomits it out. Also, the food helps only for a short time. Chachmah, as much as he increases, it helps him forever.
