ago

Ago, agere, egi, actum, third conjugation. The root sense is physical: to drive, as you drive cattle or an enemy in front of you. Everything else grows out of that push. You drive a matter forward, rem agere, "to conduct business"; you drive time along, vitam agere, "to spend a life"; and the imperative wears down into a bare interjection, age and agite, "come on then".

The trap is that ago and facio both come out as "do" in English and are not interchangeable. Facio makes a thing; ago carries on an activity. Gratias agere is "to give thanks", never "to do thanks", and actum est de nobis means "it is all over for us". The perfect egi looks unrelated to the present, which catches people. Family: actio, actor, agmen, cogo (co-ago), exigo, redigo. English act, agent, agenda, agitate, exact, cogent, ambiguous.