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The real difference between a man who has spiritual vision and discernment, and another who does not possess these faculties, is not to be found in the inmost nature of the soul; just as the clearness of vision depends, not on the latent perceptive faculty of the soul or mind, but upon the nature of the organ of vision and the tunics in which it is enveloped, the clearness of spiritual perception depends, not on the nature of the soul, but on the conditions and nature of the Upadhis [~ vehicles (*)] in which it is placed.
Consequently all progressive development consists in the improvement of the Upadhis; the soul is perfect from the beginning and undergoes not alteration during the course of evolution.
(*)The upadhis include not only the physical body, but also the emotional and the mental vehicle, to name but a few.

Subba Row, Esoteric Writings, p. 240-41
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