Vishnu and the Sun
Vishnu is the overruler of Mercury, relating to the planet as the power of intelligence, reason and discrimination (buddhi). Vishnu is the power that measures out and and regulates the cosmos. He is the indwelling cosmic intelligence that is the power of communication, love and healing. He grants discernment, detachment and clarity to his devotees, Note that this is a more specific Mercury function of Vishnu than his supreme power that is connected to the Sun. It relates more to his Trivikrama or three striding form.
Vishnu and Mercury
As Vishnu, Mercury relates to Narayana, the cosmic form of Vishnu that enters into the hearts of all creatures, as its supreme deity. Mercury on the higher level is the cosmic intelligence that is closest to the Sun of truth. For this reason, Narayana, which is often connected to Surya, relates to Mercury as well. Through the intelligence of our soul, the Divine light enters into us.
- David Frawley. Ayurvedic Astrology: Self-Healing Through the Stars. — Delhi: Lotus Press, 2007. — 288 p. — ISBN 81-208-3134-9