Ramanuja
Ramanuja (1017–1137 CE) was the philosopher who challenged Shankaracharya's Advaita with Vishishtadvaita — qualified non-dualism. Where Shankara said 'individual souls and Brahman are completely identical,' Ramanuja said: 'Individual souls and the world are real, but they are the body of Brahman — distinct within the whole.' He is the philosophical father of the Sri Vaishnava tradition and the devotional movement. He emphasised that bhakti (devotion) to Vishnu/Narayana is both valid and sufficient for liberation.
Ramanuja's key insight: love requires two. Devotion requires a lover and a beloved. For 60 seconds, feel the reality of a relationship in your life that is real precisely because there are two — not one.
Best at dusk in devotional prayer.