Spiritual tradition venerates the acharyas who are deemed as incarnations to spread the import of the Vedas and the agamas. Posterity is indebted to them as they lead the people to the path of moksha. They are thus more beneficial to people than the wish-granting divine Kalpataru.
Apart from the direct exposition of the esoteric truths in the sastras to their disciples, they have written commentaries on the Prastanatraya texts, the Brahma Sutra, the Upanishads and the Bhagavad Gita. These are the fundamental texts from which the various prevalent systems of philosophy, such as Advaita, Visishtadvaita, Dvaita, Siva Advaita, and so on have grown and developed.
In a discourse, Srimati R. Mathangi drew attention to the commentary on the Brahma Sutra by one Srikantacharya, known as the Srikanta Bashya, wherein he has established the Siva Advaita system that hails Siva as the Supreme Being. Siva is the primal source and the Supreme Lord of the whole of the universe comprising the material world and the subtle jivas. Siva possesses infinite attributes and prowess.
Also known as Siva Visishtadvaita, it explains that the entire universe comprising Chit, the sentient, and Achit, the insentient, is the sarira of Siva. The differences in the forms of jivas, and in the varieties of gunas in each and every aspect of creation, are all sustained in Siva and are manifest as the Shakti of Siva. This can be compared to a tree that is the support for the root, the trunk, the branches, the leaves, flowers and fruits, etc. These parts belong to the tree, but they also remain as individual entities with distinguishing characteristics. But though there may be many varieties of trees of similar nature, there is only one Siva, who is the Adi Siva and is Supreme, and who creates the Trimurtis.
