Existential psychology is fine as far as it goes, but can it explain the existence of extroverts? Perhaps the question indicates a misunderstanding; it is precisely directional choices of this kind, choices between active and passive engagement, that it does explain. What it points to is the common predicament for which there is no pregiven form of resolution. Choices become set, but there is no reason why they should remain so other than historical inertia, the tendency to keep to a course once taken, not because of the weight of habit but the belief in such a weight, the acceptance of historicity. This moment is only the end-point of history to the degree that historical time is acknowledged. Everything out of which your world is constructed has this equivocal quality; on examination it never proves as perfectly adapted to the case as it seems when it only forms a consideration within some other motive. It is wonderful how the household gods of the mind deliquesce under the light of attention.