"there are two faculties of intellection of which you possess one"
...a compliment and an insult together, perhaps.
1. diagrammatic method
Draw a hoop. Label its ends Plus/Minus, also: "there are two faculties of intellection"/"of which you possess one"
2. literary method
I suppose that while the meaning of the two parts of the formula are reconcileable, the intentionality you would ascribe to these parts is contradictory; but these parts are also mutually associated (rule of association).
You have a sense of yourself thinking, or an idea of your sensitivity; in any case you have a faculty and its intentionality.
Supposing the impression of correct reasoning follows from the contradiction in intention of actors; this is proscribed by Jung's formula which subsists as if intending two things at once (i.e. there's a necessary consonance of interests of actors given rule of association and its preconditions).
And the intentionality you ascribe your faculty, by itself or so prompted, is pitched against one side then the other, finding always something this faculty cannot digest.
This sense which I suppose Jung developed from something like the Book of Disquietude, of the mysterious nature of vocation (the potency of a personal faculty with respect to the potency of all faculties), illegitimately by my reckoning; this works itself out into something like the apprehension of a divine plan. This isn't a vague conservatism, but an important ideological form of conservatism, supplementing conscious self interest. Jung's affinity with the thought of the middle ages is well known.
Another example of split intentionality comes up with Percy Shelley's "unacknowledged legislator". All this is no doubt hard to understand; it's really like martian logic. But it's just outside the view of J M Keynes say, invoking "unacknowledged legislator" against ideologism, at the end of General Theory.