Nammalvar, a Tamil poet who lived in IX-X centuries, is revered as one of the great mystics of India. His four poetic works are equated with the sacred hymns and are part of the ritual worship in the temples of South India. Artistic images of Nammalvar formed the basis of the philosophy of Vishishta-Advaita several centuries later. The poem “Thiruviruttam” is considered as his early work, where he combines the canons of ancient Tamil poetry and his devoted love for Vishnu-Tirumal. The study presents a religious and philosophical interpretation of the poem. The secret of the poem is its dualism: external beauty and sacred meaning. There is a spiritual meaning in symbols of Tamil poetry. Nammalvar takes canons of his predecessors, poets of the Sangam era. However, he fills one with new content. The author compares ancient Tamil poetry and the work of Nammalvar. The plot describes the love between God and the soul. The poet reveals several types of bhakti or devoted love. The description of bhakti subsequently formed the basis for the classification of souls in the philosophy of vishishta-advaita. Bhakti leads to the transition to Vaikuntha or the heaven city. Sri Vaishnavism teachers turned the description of relationship soul-Vishnu into a spiritual practice. The artistic images of Nammalvar are compared with Hindu concepts such as transcendence, darshan, divine grace and moksha. In South India “Thiruviruttam” is considered the Tamil Rig Veda. Poem is performed at home, in the temple, during festive processes. It helps to find the roots of Vaishnavism and understand its poetic origin.