Kalach Pitchei Chokhmah and Tanya

Both texts discuss the kav (קו) as a divine conduit into the chalal (חלל), but with different emphases. Text 1 emphasizes the kav's functional role as a 'pipe' (צינור) through which divine light descends into the empty space to connect cause and effect. Text 2 emphasizes the kav as a contraction (צִמְצוּם) of infinite light that creates boundary/limitation (גְּבוּל) within souls, framing it as vessels (כְּלִים) of the sefirot. Text 1 focuses on the kav's mediating/connecting function, while Text 2 focuses on tzimtzum and the kav's role in creating defined existence within souls. Both accept kav's role but stress different aspects of its operation.