It is one of the 32 Upanishads that belongs to the Krishna Yajurveda, and is classified as one of the Samanya (general), and is one of several dedicated mystical physiology Upanishads. The text asserts that the human body is a composite of elements from earth, water, air, space (akash), and energy (agni, fire); and that the human soul (jīva) is "the lord of the [human] body". It then describes how human sensory organs arise from these, how functions such as human will, doubt, memory, intellect, copulation, speech, anger, fear, delusion, right conduct, compassion, modesty, non-violence, dharma and other aspects of life arise. The Sariraka Upanishad states that Prakriti (inert but always changing nature) consists of eight native forms, fifteen functional modifications, for a total of twenty-three tattva. It adds that the twenty fourth tattva in human body is avyakta (undifferentiated cosmic matter), asserting the individual soul functions as Kshetrajna ("the lord of the body") and the Purusha (indestructible universal principle, unchanging cosmic soul) is different and greater than the twenty four tattvas. The term śārīraka literally means "relating to the constitution of body and its parts" and "doctrine about the body and soul". The text is also called Sharirakopanishad.