, it seems that she falls into both categories of Firstness and Secondness, but she can't, since Firstness and Secondness (by definition) can have no members in common.  This leads me to conclude that Firstness, Secondness, and Thirdness are meta-classes, not classes of individuals.  Firstness has the class Person as one of its members, and Secondness has the class Mother as one of its members -- is this correct?  Mary Doe is a member of both Person and Mother, but not a member of Firstness or Secondness, b