Upon hearing, the swan thought, 'Was it you who spoke all these tales of yesterday? I am myself.'

This couplet is a masterful piece of self-realization and irony. The speaker hears something and is struck by the thought, 'Was it you?' The profound realization is that the person who complained about endless weeping and sorrow... is none other than the speaker himself. It’s a moment of bitter introspection, where the pain one laments is ultimately sourced from one's own heart. A deep commentary on self-deception.