premise: masters <mask> slaves to labor
hypothesis: the best context for <mask> here is To constrain to do or to forbear, by the exertion of a power not resistible; to compel by physical, moral, or intellectual means; to coerce; but not Any action between two bodies which changes, or tends to change, their relative condition as to rest or motion; or, more generally, which changes, or tends to change, any physical relation between them, whether mechanical, thermal, chemical, electrical, magnetic, or of any other kind.