Why is there the prefix Vov before 'Yayin'?
Rashi: Also it comes from the ground. Radak - and also it benefits man, to gladden his heart. This is if he drinks the proper amount; the Simchah improves his intellect. Nevi'im testify to this 1 .
Malbim: The third kind that the land sprouts (refer to 104:14:2:2) is trees - fruit bearing and barren. The most important fruit trees are the vine and olive tree.
Indeed, Simchah was required for Nevu'ah, and Hashem puts Shechinah on only a Chacham (Nedarim 38a). However, it says also that Shechinah rests only on a Gibor, Ashir and Anav. Does Simchah bring all these attributes?! (PF)
Does wine only gladden, but not sustain?
Brachos 35b: No, it sustains and gladdens. Bread only sustains.
What is the meaning of "Lehatzhil Panim mi'Shamen"?
Rashi: And [also] oil [comes from the ground] to make the face shine [Radak #1 - via consuming it. It says mi'Shamen, for the shine comes from the oil.]
Radak #2: This hints to one benefit of oil - lighting a lamp at night. [The prefix Mem] shows that there are other benefits, to light with it and rejoice in it.
What do we learn from "v'Lechem Levav Enosh Yis'ad"?
Brachos 35b: Bread only sustains [as opposed to wine, which sustains and gladdens].
Rashi: And [also] bread, which sustains man's heart [comes from the ground].
Radak: Nothing satiates like bread - "va'Ekchah Pas Lechem v'Sa'adu Libechem" (Bereishis 18:5). Even though the benefit is known, since the verse mentioned the benefit of wine and oil, it mentions also of bread.
Malbim: Vines and olive-trees were created to give extra pleasure, but they do not help without bread, which sustains the heart. I.e. wine gladdens and oil makes the face shine together with bread, which sustains man's heart. Without bread, wine is bitter to those who drink it, and the face will not shine.
