। ॥ ५५० ॥
In plain words
The mind, though — the mind knows everything, since it is the cause of every act of knowing. And because of that, the mind alone is the ātman; the breath, never.
Close to the Sanskrit
But the mind knows everything, [being] the cause of all cognition. Since [that is so], therefore the mind alone [is] the Self; but the vital breath, never.