[2] In the Vedas literature of Hinduism, fusion words based on tapas are widely used to expound several spiritual concepts that develop through heat or inner energy, such as meditation, any process to reach special observations and insights, the spiritual ecstasy of a yogin or Tāpasa (a vṛddhi derivative meaning "a practitioner of austerities, an ascetic"), even warmth of sexual intimacy.
[9] The term evolves to also mean "to suffer, to mortify the body, undergo penance" in order to "burn away past karma" and liberate oneself.
[11][12] Its conceptual origin is traced to the natural wait, motherly warmth and physical "brooding" provided by birds such as a hen upon her eggs - a process that is essential to hatching and birth.
[11] The Atharva Veda suggests all the gods were tapas-born (tapojās), and all earthly life was created from the sun's tapas (tapasah sambabhũvur).
[15][16] Sanskrit tapasyā (neuter gender), literally "produced by heat", refers to a personal endeavor of discipline, undertaken to achieve a goal.
[19][20] Before he reached his enlightenment, the Buddha tried asceticism (self-mortification) of the type found in other Śramaṇa religions (Jainism), and this is referred to as Tapas (Tibetan: dka' thub, Chinese: kuxing, Japanese: kugyo, Korean: kohaeng).
[10] These ancient Buddhist texts are significant in their claims of the existence of Jain Brahmins and ascetics, along with their karma doctrine and reasons for their Tapas practices in ancient times:[24] The Blessed One [Buddha] said, "There are, o monks, some ascetics and Brahmins who speak thus and are of such opinion: 'Whatever a particular person experiences, whether pleasant or painful, or neither pleasant nor painful, all this has its cause in what was previously done.
[31] In the Mahayana tradition, asceticism with esoteric and mystical meanings became an accepted practice, such as in the Tendai and Shingon schools of Japanese Buddhism.
[43] According to Walter Kaelber,[11] and others,[15][44][45] in certain translations of ancient Sanskrit documents Tapas is interpreted as austerities and asceticism; however, this is frequently inadequate because it fails to reflect the context implied, which is of sexual heat or warmth that incubates the birth of life.
[47][48] In ancient literature of Hinduism dedicated to love, desire, lust, seduction and sex, the root of the word Tapas is commonly used.
For example, in Atharva Veda, a mantra recommended for a woman who wishes to win or compel a man's love is, 'Love's consuming longing, this passion this yearning, which the gods have poured, into the waters of life, I kindle for thee (tam te tapāmi), by the law of Varuna.
[50][51] Agnicayana, Satapatha Brahmana and other ancient texts similarly use the root of the word Tapas to symbolize emotions, biological stages and a mother's effort from conception to the birth of a baby.
[54] In the Puranas and the texts of the goddess tradition of Hinduism, the term is equivalent to a devotion with intense self-discipline, believed to yield special inner powers.
[63] Oldenberg notes that Brahmana scripture suggests that the Brahmachari should carry tapas to the very tip of his existence, which includes not cutting his hair, nail and beard.
[64] Thus, during this process of spiritual rebirth and diksa, the tapas observed by a Brahmachari may include silence, fasting, seclusion, chastity, as well other activities.
[10] Ascetic Tapas among Jaina monks, both internal and external, is believed to be essential for spiritual growth and kevalya (moksha, liberation).
[69] Another Jain text Tattvartha Sutra, by Umaswati, in chapter 9, asserts that Tapas includes several kinds of meditation.
[68] Mahavira, the 24th Tirthankara undertook ascetic Tapas for twelve years, after which he attained Kevala Jnana (liberating supreme knowledge).
[77] One of the Buddhist canonical texts, Nanguttha Jataka, claims that the Ajivikas perform severe ascetic practices as part of their Tapas, including sleeping on a bed of thorns and other forms of self-mortification.
[78] The Jainism text Sthananga Sutra claims that the Ajivikas performed severe penances and self-mortification as part of their Tapas practice.