When I first started playing guitar, I remember reading a sort of dual-interview published in 1982 in the now sadly-deceased Musician magazine between Robert Fripp of King Crimson (a pretty amazing guitarist in his own right) and John McLaughlin, who, as I've written before, I think can safely be considered amongst the greatest guitarists alive:

McLaughlin: I don't meditate or fast or anything, but I reflect on the ramifications of what I do. For example, there's a relationship between two chords that you've known, that I've known, for a long time, and only recently do I begin to discover this more intimate relationship, what it means. Even though I've looked at these chords from every possible viewpoint, I'm looking for a way that maybe exists up there, but I don't know where it is. Then, a little while ago, I discovered it, it just arrived. So the work that we do, I don't think we benefit from it until later. But once we have colors and palette, the richer the palette is, the richer the music can be.

Fripp: That D major chord which changed you from a pianist to a guitarist, what color would that be for you?

McLaughlin: What color...? (pause) I think it could be green.

Fripp: Exactly what I would've said...

McLaughlin: It's got to be yellow and some blue.

Fripp: A major for me is yellow and A minor inclines toward white, which is my C major. Graham Bond said it was red.

McLaughlin: C major, red? No, E major, I would say, is red.

Fripp: E major for me is very blue, a kind of royal blue, and when you get to E minor it becomes more of a night blue, with kind of stars...

McLaughlin: That's very interesting...

Fripp: G is very greenish, but not quite.

(I wonder if Jan Hammer "suffers" from that...?)