first cause
prime mover
primum mobile

Well, the other side of being the prime mover in these things is this: I dare.

First animals and then water was used as the prime mover.

The public sector was seen as the prime mover of development.

Knowledge has always been the prime mover of prosperity and power.

But he was the prime mover of the crowd outside.

He was a prime mover in the prosecution and tried the case.

My time to stand forth as the greatest prime mover of them all will come.

But I'd say it's true enough that she wasn't the prime mover.

In his scheme economic factors are the prime mover of change.

It's almost certainly organized by the prime mover in Peace.