Kabbalah

Kav — The Thin Line of Light After Contraction

After God is said to have withdrawn the infinite light to make room for a world, Lurianic teaching describes a single narrow beam of light sent back into that emptied space to sustain the creation now forming within it.

The kav, "line" or "ray," is the thin channel of divine light Lurianic cosmology describes reentering the chalal, the empty space left after tzimtzum's contraction of the ohr Ein Sof. Where the pre-tzimtzum light filled everything without limit, the kav is deliberately narrow and measured, calibrated to sustain the developing vessels within the vacated space without overwhelming them the way the original, unrestricted light would. Luria's system treats the kav as entering the void in a specific pattern, often described as spiraling in later diagrams, establishing the first directional structure within what had been undifferentiated absence. The kav is thus the mechanism by which divine sustenance continues to reach a creation that, by design, is no longer directly saturated with the infinite light it withdrew from.