Chinese Proverb

I see, I forget.
I hear, I remember.
I do, I understand.

Moral: You can only understand something by trying it yourself

The relevance to Heavy Metal: you only understand heavy metal by listening to the songs and the bands, knowing the lyrics, knowing the fans, knowing 'what's not (and what's not)' in the heavy metal scene (in other words, what's popular and what's not), going to gigs etcetera etcetra.

Let's break it down:

1. I see, I forget: If you only see something once, say on Tv, or hear it on the radio, then you will have little chance of remembering.
2. I hear, I remember: The more you hear it, the more of it you will remember.
3. I do, I understand: But the more you immerse yourself in the scene (ie the more you do), the more you understand.