Combining the lunar nodes and Pars Fortuna into one books is a natural.
The nodal axis is the South and North Nodes of the Moon, and it is the author's thesis that these nodes refer to the type of consciousness rise that is inherent at birth and from which growth continues.
The Part of Fortune is actually a lunar Ascendant, and the author has observed that the Part of Fortune only becomes active and available in later years, as consciousness rises.
The natal Moon represents the foundation for our emotional body and it is entrained from our mother. As the years pass and we mature, we separate from what were essentially her feelings about life and about us. We then create a mature emotional structure described by Pars Fortuna, which we sometimes think of as the astral body. The fortunate part of this is that, at advanced levels of awareness, Fortuna often brings us rewards which could be called rewards for spiritual growth.