A seperate sense of self

For the reading for this week, I'd like to focus on a specific phrase that we have seen a couple times now in Jerome's letters; namely exteriorem hominem or as I've seen it mostly translated as 'the outer man' or 'outer self'.  First and foremost, it is worth noting that despite addressing the young Eustochium, Jerome's choice of phrase makes her outer self masculine, rather than something like exteriora ipsa or exteriora se.  Because of this, I wonder if Jerome is attempting to depict this outer self as something baser or diminished from the pure spirit contained inside.  He certain acknowledges that one of the aspects of the human spirit is the extreme ease with which it loves (difficile est humanam animam non amare), even if it attaches onto objects or desires of a blasphemous nature. Thus, I wonder if this 'outer being' is also represented in the same light, as Jerome acknowledges that this is the part that can be most subject to physical desire.  I also wonder if this particular phrase is acting on a preexisting tradition in earlier Christian thought, as I was able to track down the phrase later in St. Aquinas' writings on St. Paul Principale enim in homine est mens taionalis scundarium autem est natura sentitiva et corpoarlis quorum primum apostolus nominat interiorem hominem secundum exeriorem. Also, in Augustine, quia ut haec terra visibilis exteriorem hominem nutrit et continet, ita illa terra invisibilis interiorem hominem. Therefore, this distinction seems to have been widely known