 Jacobus promoted a scientific method of ancestor research that replaced reliance on oral tradition and time-honored pedigrees with primary source documentation.It was an approach made possible because of enormous efforts to preserve and index early church records and grave stone inscriptions carried out by patriotic and heraldic societies, government agencies and religious groups (particularly the Mormons) during the very years that Jacobus was starting his work.Jacobus was one of the earliest Fellows of the American Society of Genealogists, an Honor Society of fifty members chosen on the basis of the significance of their contributions to genealogy.