Music is a total constant. That's why we have such a strong visceral connection to it, you know? Because a song can take you back instantly to a moment, or a place, or even a person. No matter what else has changed in your or the world, that one song says the same, just like that moment.

This quote is saying that music is something that remains a constant no matter what else changes. Our connection to music is very powerful because it can take us right back to a particular moment or place or person. The song always says the same thing, just like the moment does, even if many other things have changed since then.