Viṣuva

Vishuva is the Sanskrit term for the equinox, the astronomical moment when the duration of day and night are equal. The Hindu calendrical tradition recognizes two Vishuvas each year: Vasanta Vishuva (vernal equinox) and Sharad Vishuva (autumnal equinox), marking the Sun's crossing of the celestial equator. These points serve as critical reference markers in Jyotish Shastra for calculating tithis, nakshatras, and seasonal rites.

Vishuva represents the cosmic principle of samatva (equanimity), the precise threshold where opposing forces—light and darkness, pravritti and nivritti—stand in perfect equilibrium. It symbolizes the aspirant's inner balance point where worldly engagement and spiritual withdrawal are held in equal measure. Meditating on Vishuva cultivates awareness of the still center within the perpetual oscillation of the gunas.

At the absolute level, Vishuva points beyond all duality to the unchanging substratum that makes the play of opposites possible. Just as the equinox is neither day nor night yet gives rise to both, Brahman is the non-dual ground transcending and encompassing all pairs of opposites. Vishuva is thus a temporal symbol of the timeless—Turīya, the fourth state beyond waking, dreaming, and deep sleep.