3 - Extroverts and Introverts
The key point here is that (possessive) attachment to phenomena is always associated with an imbalance in understanding, whereby meaning is exclusively identified with just one arbitrary pole of development.
When this is the case, objects assume a rigid identity in experience (which tends to block out the pure light of Spirit).
So the development at H1 is a continual lesson in bi-directional understanding (with respect to horizontal polarities).
Thus starting from initial identification with the exterior pole, we continually train ourselves to recognise that the opposite pole is always necessarily involved in experience.
Success in such phenomenal training leads to growing recognition of the paradoxical nature of all dualistic truth. This in turn helps to lessen exclusive identity with arbitrary poles and enables growing transformation in nondual spiritual insight.
However total success in freeing oneself from rigid identification with (horizontal) poles is unlikely to be achieved at H1.
Personality characteristics can be very important. Some are naturally extroverts while others are introverts. Though in the truest sense, all who are destined for substantial spiritual development are centroverts, secondary personality characteristics are likely to remain.
Thus an extrovert might experience special difficulty in achieving freedom from (exclusive) identification with the exterior aspect; however the introvert will typically experience greater difficulty with respect to the interior aspect.
Thus in the mystical life an appropriate form of purgation for the extrovert would be the growing concentration on interior development; however for the introvert, appropriate purgation could entail more active involvement in everyday affairs.