A regular periodical current of water, setting alternately in a flux and reflux, and generally considered to be produced by the influence of the moon. The sagacious Locke, in describing the theory of the tides, observes, "that motion of the water called the tides, is a rising and falling of the sea; the cause of this is the attraction of the moon, whereby the part of the water in the great ocean, which is nearest the moon, being most strongly attracted, is raised higher than the rest; and these two opposite elevations of the surface of the water in the great ocean, following the motion of the moon from east to west, and striking against the large coasts of the continents, from thence rebound back again, and so make floods and ebbs in narrows, seas, and rivers.