There is, however, one conspicuous feature of North American antiquity which has not yet received our attention, and which calls for a few words before we close this chapter. I refer to the mounds that are scattered over so large a part of the soil of the United States, and more particularly to those between the Mississippi river and the Alleghany mountains, which have been the subject of so much theorizing, and in late years of so much careful study.[155] Vague and wild were the speculations once rife about the "Mound-Builders" and their wonderful civilization. They were supposed to have been a race quite different from the red men, with a culture perhaps superior to our own, and more or less eloquence was wasted over the vanished "empire" of the mound-builders. There is no reason, however, for supposing that there ever was an empire of any sort in ancient North America, and no relic of the past has ever been seen at any spot on our planet which indicates the former existence of a vanished civilization even remotely approaching our own. The sooner the student of history gets his head cleared of all such rubbish, the better. As for the mounds, which are scattered in such profusion over the country west of the Alleghanies, there are some which have been built by Indians since the arrival of white men in America, and which contain knives and trinkets of European manufacture. There are many others which are much older, and in which the genuine remains sometimes indicate a culture like that of Shawnees or Senecas, and sometimes suggest something perhaps a little higher. With the progress of research the vast and vague notion of a distinct race of "Mound-Builders" became narrowed and defined. It began to seem probable that the builders of the more remarkable mounds were tribes of Indians who had advanced beyond the average level in horticulture, and consequently in density of population, and perhaps in political and priestly organization. Such a conclusion seemed to be supported by the size of some of the "ancient garden-beds," often covering more than a hundred acres, filled with the low parallel ridges in which corn was planted. The mound people were thus supposed to be semi-civilized red men, like the Aztecs, and some of their elevated earthworks were explained as places for human sacrifice, like the pyramids of Mexico and Central America. It was thought that the "civilization" of the Cordilleran peoples might formerly have extended northward and eastward into the Mississippi valley, and might after a while have been pushed back by powerful hordes of more barbarous invaders. A further modification and reduction of this theory likened the mound-builders to the pueblo Indians of New Mexico. Such was the opinion of Mr. Morgan, who offered a very ingenious explanation of the extensive earthworks at High Bank, in Ross county, Ohio, as the fortified site of a pueblo.[156] Although there is no reason for supposing that the mound-builders