I would recommend reading this with the Blue Heart’s Rose of Passion in the background. You can find a few versions including a live one on YouTube.
The lyrics themselves are about whe=ther it’s possible for anything to be eternal and unchanging in the face of time. In the end, that thing is buried deep in your heart, deep in your brain, found in all small happy moments and unhappy moments.
I believe the reason it’s cited here is that the song is saying: though things may change and people leave us, the love remains.
Thanks Gouma-Den for the translation.