What do we learn from "Al Tere Yayin Ki Yis'adam"?
Sanhedrin 70a #1: Do not be drawn after wine, for it reddens the faces of Resha'im (gladdens them) in this world and whitens their face (shames them) in the world to come.
Sanhedrin 70a #2: Do not be drawn after wine, for Yis'adam (it leads to bloodshed).
Menachos 87a: Rebbi says, we do not bring old wine for Nesachim. (Wine should be red. After one year, the redness fades.)
Bava Basra 97b: White wine is not acceptable [for Nesachim; some say, for Kidush].
Pesachim 108b: The wine for the four cups must have the appearance of wine.
Rashi: Do not put your eyes on red wine.
R. Yonah: Do not look at its appearance when it is red, lest your desire increase to drink more.
Malbim: Do not desire wine because you see that it is red. This shows that it is good wine, and benefits the blood, which is the Nefesh Chiyuni.
Why does it say "Ki Yiten ba'Kos Eino Yis'halech b'Meisharim"?
Rashi: One who increases inebriety, all Aveiros seem straight to him. All ways are straight in his eyes.
R. Yonah: He looks at its nice appearance. This is like "k'Ein ha'Bedolach" (Bamidbar 11:7). Them he will want to drink much.
Malbim: First he puts his eye on the color [of the wine] and the cup in which it was put, and then he goes straightly, as if there is no problem with it. The metaphor is, one who drinks a cup with wine, he becomes red like the wine. The beginning of the drinking repast is straight and pleasant. However, [its end bites like a snake - 32].
Why is it written ba'Kis, and we pronounce it ba'Kos?
Rashi: One who drinks put his eye on the cup. The grocer puts his eye on the wallet of the one who drinks (he receives his money for the wine).
