Samakh means to lean or to press. Semikhah is the leaning of hands, the act by which Moshe pressed his hands on Yehoshua bin Nun and the people saw authority pass from one man to another (Numbers 27:18-23, Deuteronomy 34:9). The gesture is ancient and biblical. The institution built on it is not. Rabbinic semikhah, the ordination chain in which a certified teacher confers standing on a student who can then confer it on his own students, is machinery of the post-70 world, the rabbinate's answer to a shattered Temple and a scattered people.

The chain matters because a chain has a gate. Once authority travels by semikhah, you must be on the chain to speak with standing, and someone controls admission. That is the difference between teaching as work and teaching as rank. The early assemblies of Yeshua's followers laid hands on people too (Acts 6:6, 1 Timothy 4:14), but the Didache still told each assembly to raise its own overseers from among themselves. The gesture was the same. The monopoly was the innovation.