My song of dawn fell into your darkness, and a flash of brilliance/spark that was hidden beneath my ashes emerged.

This profound couplet speaks of the complex nature of love and self-discovery. The poet suggests that while he offered his purest joy—his 'morning song'—to the beloved's path, the true, volatile passion (the 'spark') was not directed outward. Instead, it was hidden deep within his own being, concealed even beneath the dust of his own existence. It's a powerful statement about finding the most intense fire not in the destination, but within the self.