"When you are drunk, all you can see is light", is a line used in a long drunken monologue by the Ol' Dirty Bastard on his 1996 album Return to the 36 Chambers- The Dirty Version. The actual words that he uses may be slightly different, and are probably more profanity laced.
The line actually occurs in the a song called Brooklyn Zoo II - Tiger Crane, where Ol' Dirty is discussing the need to take rap seriously, and that rappers should approach rap with the same intensity that a man would want to murder an adulterous girlfriend and her lover. (Of course, he puts it in quite different terms). I had always taken the line to just be an explanation of how when someone is full of single minded rage, especially liquor filled rage, the world turns into a blob of light.
A few years ago, I was in the habit of saying "when you are drunk, all you can see is light" in much the same context that Cowboy Neal is mentioned in Slashdot Polls, that is in no context at all. Well, one time, I mentioned this out of nowhere, and the girl I was talking to replies, automatically "well, of course! All you can ever see is light", an answer that had never occured to me up to that point. After all, all we ever see is the light hitting our eyes.
I soon noticed that when I asked people whether the phrase was true, that quite a few people said that was nonsense, and that of course you could see the same thing when you are drunk as at other times. A large minority, however, would reply much as that friend had, pointing out that all you could ever see is light. Also, people's responses didn't seem to have much correspondence with their conventional or unconventional intelligence, or common sense, or expererience with alcohol. Some people got it, some people didn't.
As for whether the ODB was trying to make a philosophical statement about the nature of perception, or whether he was just making shit up off the top of his head, I don't know. Ol Dirty, if you are reading this, please msg me and tell me! (It looks like Ol Dirty will not get back to me on the matter, since he has passed away. RIP, ODB)