About this time President Stiles, of New Haven, Dr. Franklin, Dr. Barton, and a few other leading minds of that day, becoming thoroughly convinced of the existence of these antiquities, and having received descriptions of a number of them, began to advance theories as to their origin. William Bartram had come to the conclusion, from personal observation and from the statement of the Indians that "they knew nothing of their origin," that they belonged to the most distant antiquity.

Dr. Franklin, in reply to the inquiry of President Stiles, suggested that the works in Ohio might have been constructed by De Soto in his wanderings. This suggestion was followed up by Noah Webster with an attempt to sustain it,[44] but he afterwards abandoned this position and attributed these works to Indians.

Captain Heart, in reply to the inquiries addressed to him by Dr. Barton, gives his opinion that the works could not have been constructed by De Soto and his followers, but belonged to an age preceding the discovery of America by Columbus; that they were not due to the Indians or their predecessors, but to a people not altogether in an uncultivated state, as they must have been under the subordination of law and a well-governed police.[45]

This is probably the first clear and distinct expression of a view which has subsequently obtained the assent of so many of the leading writers on American archæology.

About the commencement of the nineteenth century two new and important characters appear on the stage of American archæology. These are Bishop Madison, of Virginia, and Rev. Thaddeus M. Harris, of Massachusetts.

Dr. Haven, to whose work we are indebted for reference to several of the facts above stated, remarks:

These two gentlemen are among the first who, uniting opportunities of personal observation to the advantages of scientific culture, imparted to the public their impressions of western antiquities. They represent the two classes of observers whose opposite views still divide the sentiment of the country; one class seeing no evidence of art beyond what might be expected of existing tribes, with the simple difference of a more numerous population, and consequently better defined and more permanent habitations; the other finding proofs of skill and refinement, to be explained, as they believe, only on the supposition that a superior race, or more probably a people of foreign and higher civilization, once occupied the soil.[46]

Bishop Madison was the representative of the first class. Dr. Harris represented that section of the second class maintaining the opinion that the mound-builders were Toltecs, who after leaving this region moved south into Mexico.

As we find the principal theories which are held at the present day on this subject substantially set forth in these authorities, it is unnecessary to follow up the history of the controversy except so far as is required to notice the various modifications of the two leading opinions.

Those holding the opinion that the Indians were not the authors of these works, although agreeing as to this point and hence included in one class, differ widely among themselves as to the people to whom they are to be ascribed, one section, of which, as we have seen, Dr. Harris may be considered the pioneer, holding that they were built by the Toltecs, who, as they supposed, occupied the Mississippi Valley previous to their appearance in the vale of Anahuac.