…as the basis for distinction is in the person's capacity
and ability, and differences are related to the degree of his intelligence and mental
powers, therefore, all the people will not be equal in their knowledge,
learning and understanding. The intent is to say that the world of creation
calls for distinctions in people's stations, and degrees in the differences
existing among them, so that the affairs of the world may become organized and
ordered. Diversity in all created things, whether in kind, in physical
appearance, or in station, is the means for their protection, their permanence,
unity and harmony. Each part complements the other.
(From a letter dated 22 May 1928 written on behalf of Shoghi Effendi to an individual believer, translated from Persian;The Compilation of Compilations, vol. III, Economics, Agriculture, and
Related Subjects)