One’s spiritual progress implies subordinating ego to the enlightened soul

… the complete and entire elimination of the ego would imply perfection -- which man can never completely attain -- but the ego can and should be ever-increasingly subordinated to the enlightened soul of man. This is what spiritual progress implies. (From a letter dated 14 December 1941 written on behalf of Shoghi Effendi to an individual believer; The Compilation of Compilations vol II, p. 11)