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The difference between "machines" and "engines" is obviously this, that machines need more workmen and greater power to make them take effect, as for instance ballistae and the beams of presses. Engines, on the other hand, accomplish their purpose at the intelligent touch of a single workman...

"De architectura (Ten Books on Architecture)". Book by Marcus Vitruvius Pollio (Book X, Chapter I, Section 3), circa 15 BC.
The difference between machines and engines is obviously this, that machines need more workmen and greater power to make them take effect, as for instance ballistae and the beams of presses. Engines, on the other hand,