Background Shiva is Energy in matter domain. Shiva is consciousness in biological domain. In matter domain, Shakti is the momentum through which Shiva, the energy, is expressed or perceived. In biological domain, Shakti is the 'Signaling' through which Shiva, the consciousness is expressed or perceived. In matter domain, Shakti and Shiva are Energy-Momentum couple. They are ardha-nArIsvara. They cannot be separated. In biological domain, Shiva and Shakti are the consciousness-signaling couple. They cannot be separated. Vid means to know. Vidya is that is known or learnt. mahA-vidyAs are 'greatly known' or 'well learnt' forms of Shakti. Shodasi In matter domain, Shiva-Shakti, the Energy-Momentum couple fills this three dimensional empty space that is common to all the three worlds. Hence Shakti is called tripura-sundari. This tripura-sundari is perceived in 16 different ways. Hence she is called Shodasi. In biological domain, Shiva-Shakti is also the Conscious