Brahma, Vishnu, Shiva are only three Powers and Personalities of the One Cosmic Godhead. page 390 , Letters on Yoga , volume 22 , SABCL

Mahashiva means a greater manifestation than that ordinarily worshipped as Shiva – the creative dance of a greater Divine manifesting Power. Shiva is the Lord of Tapas. The power is the power of Tapas. Krishna as a godhead is the Lord of Ananda, Love and Bhakti; as an incarnation, he manifests the union of wisdom (Jnana) and works and leads the earth-evolution through this towards union with the Divine by Ananda, Love and Bhakti. page 391 , Letters on Yoga , volume 22 , SABCL