h₂eǵ-

The root *h₂eǵ- encodes a semantic field spanning physical driving (of animals, vehicles) and abstract leading (of people, affairs). Its extraordinary productivity in Latin alone has embedded it deeply in the modern European vocabulary. Latin agere ("to drive, to do, to act") is the pivotal reflex. The participial form āctus yields act, action, actual, and exact (ex-āctus, "driven out, completed"). The agential suffix -ātor gives actor. Compounds of agere pervade English: navigate (nāvis + agere, "to drive a ship"), litigate (līs + agere, "to drive a lawsuit"), fumigate (fūmus + agere, "to drive with smoke"), ambiguous (ambiguus, "driving both ways"), cogent (cōgēns, "driving together," hence "compelling"), exigent, prodigal (prōdigere, "to drive forth," hence "to squander"), and agent (agēns, "one who drives"). Greek ágō (ἄγω, "I lead") underlies pedagogue (paidagōgós, "child-leader"), demagogue (dēmagōgós, "people-leader"), synagogue (synagōgḗ, "a leading together"), and stratagem (stratḗgēma, from stratēgós, "army-leader"). The semantic shift from "driving" to "leading" is characteristic of Greek. Sanskrit ájati ("drives") shows the expected palatal treatment. The Avestan cognate azaiti confirms the Indo-Iranian form. In Germanic, the reflex is debated, but Old Norse aka ("to drive") and possibly Old English acan (related to ache, if from the sense of "being driven" by pain) have been proposed. The limited Germanic attestation contrasts sharply with the root's productivity in Italic and Greek. Old Irish ad-aig ("drives") and Lithuanian agóti ("to herd") extend the attestation to Celtic and Baltic. The consistent semantic core of driving and leading across all branches confirms the antiquity and stability of this root.