The poet's asking, "What is the meaning of life?"
Kumud Biswas's translation of জানি গো, দিন যাবে এ দিন যাবে / jaani go, din jaabe e din jaabe strikes me as a bit inept. Bengali nouns have the same form in singular and plural, and in at least two critical places I think she mistranslates by substituting one for the other.
The lyric is about the poet's knowledge that his life will come to an end eventually. It therefore makes more sense to treat the word দিন / din, "day", as plural rather than singular: "I know these days will pass" rather than "I know this day will come to an end".
In the line you ask about, too, I disagree with the translation:
Why the lights of the day
Raised waves in my mind –
I would translate পরানে ঢেউ তুলেছিল কেন দিনের জ্যোতি / paraane Dheu tulechhila kena diner jyoti as: Why did the light of day agitate/quicken my soul? It's true that ঢেউ তুলেছিল / Dheu tulechhila is literally raised waves, but the sense is idiomatic. It's rather like the English expression make waves: stir things up, agitate matters, except that the connotation isn't necessarily negative in Bengali.
The song lyric is about the poet's knowledge that his time on earth will end eventually. It is his prayer that before he dies, he understand why he was given life in the first place. Tagore moves between the literal and the metaphoric seamlessly throughout the poem. When he asks why daylight stirs his heart, he's asking, on the one hand, why he is moved by the experience of daylight. More fundamentally, he's asking why his soul was awakened at all; why, instead of a dark nothingness, he actually experiences light and life.
Consider the idiom never see the light of day. It means, basically, something that doesn't ever come into being. Tagore is asking why he did see the light of day. What is the reason he was brought into being?
That's a good reason to use quicken rather than agitate in the translation, actually. Quicken can mean both "make faster" and "make alive", and that sort of double meaning is very much a part of Tagore's strategy in in his seamless blend of literal and metaphoric in this lyric. It's true that the word "quicken" has no literal counterpart in the lyric, but a literal "raise waves" is slavishly faithful while completely obscuring the deftness of Tagore's poetry.
Translating জ্যোতি / jyoti as "lights" rather than "light", and treating the waves literally, obscures the literal and metaphoric sense of the line in an unfortunate way.
- My Bengali is dreadful. Rely on translations above AYOR.
- Bengali transliteration follows the iTrans scheme.
- Here is a recording of the song by Suchitra Mitra. Lyrics and music are of course Tagore's.
- Obiter dicta: October/November 2020 was when I realized exactly how poorly Tagore has been served by translations, even his own. The dude really deserved that Nobel, and you'd never know it reading his works in the available English translations.