Sa?s?ra (Sanskrit: ?????) means "wandering", as well as "world" wherein the term connotes "cyclic change". Sa?s?ra is a fundamental concept in all Indian religions, is linked to the karma theory, and refers to the belief that all living beings cyclically go through births and rebirths. The term is related to phrases such as "the cycle of successive existence", "transmigration", "karmic cycle", "the wheel of life", and "cyclicality of all life, matter, existence". Many scholarly texts spell Sa?s?ra as Samsara.

According to Monier-Williams, Sa?s?ra is rooted in the term Sa?s? (????), which means "to go round, revolve, pass through a succession of states, to go towards or obtain, moving in a circuit". A conceptual form from this root appears in ancient texts as Sa?sara?a, which means "going around through a succession of states, birth, rebirth of living beings and the world", without obstruction. The term shortens to Sa?s?ra, referring to the same concept, as a "passage through successive states of mundane existence", a transmigration, metempsychosis, a circuit of living where one repeats previous states, from one body to another, a worldly life of constant change, that is rebirth, growth, decay and redeath. The concept is then contrasted with the concept of moksha, also known as mukti, nirvana, nibbana or kaivalya, which refers to liberation from this cycle of aimless wandering.

The concept of Samsara developed in the Vedic times, and is traceable in the Samhita layers such as in sections 1.164, 4.55, 6.70 and 10.14 of the Rigveda. While the idea is mentioned in the Samhita layers of the Vedas, there is lack of clear exposition there, and the idea fully develops in the early Upanishads. Damien Keown states that the notion of "cyclic birth and death" appears around 800 BCE. The word Sa?s?ra appears, along with Moksha, in several Principal Upanishads such as in verse 1.3.7 of the Katha Upanishad, verse 6.16 of the Shvetashvatara Upanishad, verses 1.4 and 6.34 of the Maitri Upanishad.

The word Samsara is related to Sa?s?ti, the latter referring to the "course of mundane existence, transmigration, flow, circuit or stream".

The word literally means "wandering through, flowing on", states Stephen J. Laumakis, in the sense of "aimless and directionless wandering". The concept of Sa?s?ra is closely associated with the belief that the person continues to be born and reborn in various realms and forms.

The earliest layers of Vedic text incorporate the concept of life, followed by an afterlife in heaven and hell based on cumulative virtues (merit) or vices (demerit). However, the ancient Vedic Rishis challenged this idea of afterlife as simplistic, because people do not live an equally moral or immoral life. Between generally virtuous lives, some are more virtuous; while evil too has degrees, and the texts assert that it would be unfair for god Yama to judge and reward people with varying degrees of virtue or vices, in "either or" and disproportionate manner. They introduced the idea of an afterlife in heaven or hell in proportion to one's merit, and when this runs out, one returns and is reborn. This idea appears in ancient and medieval texts, as the cycle of life, death, rebirth and redeath, such as section 6:31 of the Mahabharata and section 6.10 of Devi Bhagavata Purana.

The historical origins of a concept of a cycle of repeated reincarnation are obscure but the idea appears in texts of both India and ancient Greece during the first millennium BCE.

The idea of Samsara is hinted in the early Vedic texts such as the Rigveda, but the theory is absent. The early textual layers of the Vedas mention and anticipate the doctrine of Karma and rebirth, however states Stephen Laumakis, the idea is not fully developed. It is in the early Upanishads where these ideas are more fully developed, but there too the discussion does not provide specific mechanistic details. The detailed doctrines flower with unique characteristics, starting around the mid 1st millennium BCE, in diverse traditions such as in Buddhism, Jainism and various schools of Hindu philosophy.

Some scholars state that the Samsara doctrine may have originated from the Sramana traditions and was then adopted by the Brahmanical traditions (Hinduism). The evidence for who influenced whom in the ancient times, is slim and speculative, and the odds are the historic development of the Samsara theories likely happened in parallel with mutual influences.

Punarmrityu: redeath

While Sa?s?ra is usually described as rebirth and reincarnation of living beings, the chronological development of the idea over its history began with the questions on what is the true nature of human existence and whether people die only once. This led first to the concepts of Punarm?tyu ("redeath") and Punarav?tti ("return"). These early theories asserted that the nature of human existence involves two realities, one unchanging absolute Atman (soul) which is somehow connected to the ultimate unchanging immortal reality and bliss called Brahman, and that the rest is the always-changing subject (body) in a phenomenal world (Maya). Redeath, in the Vedic theosophical speculations, reflected the end of "blissful years spent in svarga or heaven", and it was followed by rebirth back in the phenomenal world. Samsara developed into a foundational theory of the nature of existence, shared by all Indian religions.

Rebirth as a human being, states John Bowker, was then presented as a "rare opportunity to break the sequence of rebirth, thus attaining Moksha, release". Each Indian spiritual tradition developed its own assumptions and paths (marga or yoga) for this spiritual release, with some developing the ideas of Jivanmukti (liberation and freedom in this life), while others content with Videhamukti (liberation and freedom in after-life).

The Sramanas traditions (Buddhism and Jainism) added novel ideas, starting about the 6th century BCE. They emphasized human suffering in the larger context, placing rebirth, redeath and truth of pain at the center and the start of religious life. Samsara was viewed by the Sramanas as a beginningless cyclical process with each birth and death as punctuations in that process, and spiritual liberation as freedom from rebirth and redeath. The samsaric rebirth and redeath ideas are discussed in these religions with various terms, such as ?gatigati in many early Pali Suttas of Buddhism.

Evolution of ideas

Across different religions, different soteriology were emphasized as the Sa?s?ra theories evolved in respective Indian traditions. For example, in their Sa?s?ra theories, states Obeyesekere, the Hindu traditions accepted Atman or soul exists and asserted it to be the unchanging essence of each living being, while Buddhist traditions denied such a soul exists and developed the concept of Anatta. Salvation (moksha, mukti) in the Hindu traditions was described using the concepts of Atman (self) and Brahman (universal reality), while in Buddhism it (nirvana, nibbana) was described through the concept of Anatta (no self) and ??nyat? (emptiness).^[63][64]

The Ajivika tradition combined Sa?s?ra with the premise that there is no free will, while the Jainism tradition accepted the concept of soul (calling it "jiva") with free will, but emphasized asceticism and cessation of action as a means of liberation from Sa?s?ra it calls bondage.^[65][66] The various sub-traditions of Hinduism, and of Buddhism, accepted free will, avoided asceticism, accepted renunciation and monastic life, and developed their own ideas on liberation through realization of the true nature of existence.^[67]