Lyric discussion by totycro 

Cover art for Cleansing Rain lyrics by Mors Principium Est

I see a number of more or less simple metaphors in there, e.g. the drums as drops, which are rain- and teardrops at the same time.

First stanza: The protagonist cries, and it burns, still s/he feels it is the right thing, s/he want's it to continue.

Second stanza: The sun, the pleasant part of life, makes him/her uncomfortable, and creates a craving for the known cave, the tears, perhaps the depression, to hide. But there, the tears make the moon look silver, that could represent something precious or a feeling of order or beauty (the moon is supposed to be silver, and that's beautiful).

The tears keep him/her busy with mourning, also blind to the world. "Enslaved with grief", as Anathema might say. Still it feels like a catharsis, a time to go through in order to deal with something that has happened. For now, the tears are a second skin that covers the protagonist from the outside world, and maybe they will someday have cleansed the inner self, so that the cave can be escaped from, or maybe not; it's not know at this point in time.

Not sure if there's a deeper meaning beyond this.