Mathaii was a highly educated individual who had left a very well-to-do life in Europe to come with Kelpius to the colonies.  Documented incidents of his psychic development can be found in 20th Century issues of the Rosicrucian Digest. 

During Beissel’s first year in the colonies, he was in close association with Mathaii.  It is recorded, though that—as time went on—not all was well between Beissel and other Rosicrucian leaders in Pennsylvania.