A well-worn path, (not) the usual route or method. The origin seems obvious, since a much-used route would indeed be flattened by the tramp of many feet. The phrase began to be used figuratively, in the sense of trite or unoriginal, in the seventeenth century or before, and off the beaten track, in the meaning of new or unusual, is just about as old. Samuel Johnson spelled it out in 1751 when he wrote, “The imitator treads a beaten walk.”