The tattvas in Indian philosophy are elements or principles of reality. Tattvas are the basic concepts to understand the nature of absolute, the souls and the universe in Samkhya and Shaivite philosophies. Samkhya philosophy lists 25 tattvas while later Shaivite philosophies extend the number to 36. Tattvas are used to explain the structure and origin of the Universe. They are usually divided into three groups: śuddha (pure tattvas); śuddhaśuddha (pure-impure tattvas); and aśuddha (impure tattvas). The pure tattvas describe internal aspects of the Absolute; the pure-impure tattvas describe the soul and its limitations; while the impure tattvas include the universe and living beings that assist the existence of soul. Overview Tattva () is a Sanskrit word meaning 'thatness', 'principle', 'reality' or 'truth'. Samkhya philosophy enumerates only 25 tattvas; twenty-four ātma tattvas along with purusha, which is ātman or the soul. Shaivite philosophies elaborate on these, taking the twenty-four ātma tattvas as the aśuddha (impure) tattvas and adding to them the śuddhāśuddha (pure-impure) and śuddha (pure tattvas), enumerating thirty-six distinct tattvas, with purusha being counted among the śuddhāśuddha tattvas. According to the early Shaivite philosophies, Parameshwara or Parashiva (also spelled Paramashiva, Paramshiva, Parmshiva) is the ultimate reality or Parabrahman, "the one form where everything emerges". The nondualistic monism school of Shaivism, Kashmir Shaivism, describes the tattvas as Paramshiva manifests himself by a process of descent from Paramashiva to jiva, through the 36 tattvas. The vibrant creative energy of Parashiva, known as Spanda, moves him to manifest himself these 36 tattvas as a līlā or divine play. Some teachings treat Parameshwara and Parashiva, along with Parashakti, as three separate aspects of Shiva. Another important sect of Shaivism, Shaiva Siddhanta, a school that show both Monistic and dualistic qualities, describes the tattvas in a different perspective. Passive Parameshwara is activated itself by śuddha māyā or divine grace (Shakti) of him. Like that, the universe, (Prakriti) is activated by aśudda māyā (physical body and all aspects of universe), another aspect of divine grace - Mahamaya. The interaction of Pure Maya and Impure Maya is the Pure - impure Maya where the souls (Pashus) attain knowledge which leads to the existence of whole universe. Mahāmāyā divides itself into three aspects: śuddha māyā, śuddha-aśuddha māyā, and aśuddha māyā, and causes five, seven, and twenty-four tattvas respectively. Five pure tattvas Suddha tattvas, also known as Śaiva tattvas are functioning in the absolute level which leads to the