The Yoga Shikha Upanishad probably originated from the 13th century. This extract from the first chapter perhaps present the earliest known tantric view of Hatha yoga and Raja yoga. This Upanishad is also the oldest text in which the two terms are defined.


Raja yoga described as the union of male semen (Retas (रेतस्, Retas)) with female vaginal secretion (Rajas (रजस्, Rajas)) (YSU I.137).This interpretation of Raja yoga was often literally translated particularly in tantric Kaula (कौल, Kaula) schools. In other tantric traditions, Raja-Yoga (रजयोग, Raja-Yoga) is often translated as the union of Shiva (शिव, Śiva) and Shakti (शक्ति, Śakti), the male and female beings.Modern interpretations of the term Raja yoga usually gloss over these tantric ideas.


Sentence 130

eka eva chaturdha.ayam maha-yogo-.abhidhiyate |"
hakarena bahiryati sakarena vishet-punah ||130||

एक एव चतुर्धा.अयं महायोगो.अभिधीयते ।"
हकारेण बहिर्याति सकारेण विशेत्पुनः ॥१३०॥

eka eva caturdhā.ayaṁ mahā-yogo-.abhidhīyate ।"
hakāreṇa bahiryāti sakāreṇa viśet-punaḥ ॥130॥

this is indeed a unique fourfold Maha-Yoga. |
Exhale with the sound HA and inhale again with the sound SA, ||130||

eka (एक, eka) = alone, one
eva (एव, eva) = indeed, really, alone
chaturdha (चतुर्धा, caturdhā) = fourfold, in four pieces
ayam (अयम्, ayam) = this, here
maha (महा, mahā) = great, large
maha-yoga (महायोग, mahā-yoga) = Maha Yoga
abhidhiyate (अभिधीयते, abhidhīyate) = is known as
hakarena (हकारेण, hakāreṇa) = through the sound / character "ha"
bahiryati (बहिर्याति, bahiryāti) = exhale, push out
sakarena (सकरेण, sakareṇa) = through the sound / character "sa"
vish (विश्, viś) = come into, enter, inhale
punar (पुनर्, punar) = back, in opposite direction, again