Hansa Gita: The Song of a Divine Swan

Whatever we see, hear, or think by our mind is constituted by three attributes of nature; viz. Sattva, Rajas, and Tamas. We can also call them righteousness, activity, and ignorance. These three attributes of nature cause our current afflictions and the past and future transmigrations. If one can subdue their effects, he attains final emancipation. The surest way for it is the devotion to the Lord with the consistency of purpose.

When we exhale or breathe out, it generates a sound like 'ha(n)'. Similarly, when we inhale or breathe in, it generates a sound like 'sa'. Their combination is Hansa or the soul, which remains unchanged during this breathing process. Hence, in Vedic Philosophy, a swan is a metaphor of a pure soul.