These are the two birds, which are immutable, which are friends, and which should be known as unintelligent. That other who is different from these two is called the Intelligent.
द्वाविमौ पक्षिणौ नित्यौ संक्षेपौ चाप्यचेतनी। एताभ्यां तु परो योऽयश्चेतनावान् स उच्यते॥