In other words, why is Krishna blue and Radha golden?
The tantric explanation for the symbolic colors of Krishna’s blue and Radha’s golden bodies is that these eternal lovers represent the creative lightning flash of Shakti and the blue ocean of Shiva. Tantric lovers representing yogic nondual union.
When we look at the ocean from afar its surface appears to be blue, but if we cup some ocean waters in our hands, then the ocean is transparent. The same holds true if we come close to the transparent being of Consciousness, of Shiva, of Krishna.
He appears blue from a distant, but up close, through our nondual gaze of meditational ecstasy, the Blue Krishna becomes transparent, as transparent as Consciousness, as Shiva Himself.
Hence Krishna is the devotional aspect of Shiva, of Consciousness. In tantric philosophy, in yogic philosophy, the devotional Krishna is the same as Purusha, the same as Consciousness.
So, when we chant the name of Krishna during kirtan, we sing the praises of Consciousness. The heart-melting blue boy represents nondual awareness, nondual Consciousness, the nondual God Shiva, nondual Purusha. Many names, some devotional (Krishna), some tantric (Shiva), some philosophical (Purusha) for the same nondual aspect of reality.
The sensuous and captivating consort Radha likewise takes part in her divine play with her lover Krishna and represents the creative aspect of nondual reality, that which creates the world of form. She is Shakti, the Goddess of creation; she is Prakriti.
Together Radha and Krishna dance and merge into one single current of nondual delight. They are not two; they are One.
As per tantra, you cannot realize the Absolute Divine without dancing in the world of the relative. Without dancing, moving, expressing in the form of a human body; we cannot experience the ethereal and Divine. Thus the body too is Divine.
Likewise, you cannot truly understand the traps of relativity without knowing the vast radiance of the Absolute. Thus the arms flung ecstatically toward the sky and the feet firmly rooted on the earth are One Body.
Krishna’s love is focused on the sparkling eyes of Radha. And her loving being plunges into the vast ocean of Krishna’s gaze. Thus the Absolute Krishna is expressed through the eyes of the relative reality of Radha. Two cosmic beings, One Cosmic Love.
That’s the tantric story of the two radiant lovers—Radha and Krishna. Hence yoga, from a tantric perspective, is both worldly and otherworldly, both physical and metaphysical.