From which essay of Ralph Waldo Emerson have these lines been taken? “Perhaps the time is already come when it ought to be, and will be something else; when the sluggard intellect of this continent will look from under its iron lids and fill the postponed expectation of the world with something better than the exertions of mechanical skill. Our day of dependence, our long apprenticeship to the learning of other lands, draws to a close.”