I don't find this tragic, because of all the references to light. It is not talking about being lost in darkness. There are a lot of references to light.Lost as a light is lost in light.
It seems to me a supplication, a desire to achieve Nirvana. Which, I am told, is a feeling of bliss, of being at one. Apparently our word 'atonement' comes from this 'at one ment'.
It reminds me of that psalm.....As the hart panteth for water, so does my soul thirst for thee, Oh Lord.
Isn't it odd, how such a passionate poem can mean such different things to us? I suppose it has to do with where ones preoccupations lie.