The third power of man [next to his soul and mind] is the power of the Spirit. It is an emanation from the Divine Bestower. It is the effulgence of the Sun of Reality, the radiation of the celestial world. In short it is the essence of the Spirit of Faith of which His Holiness Christ speaks when He says, 'Those that are born of the flesh are flesh and those that are born of the spirit are spirit." The spirit is the axis around which the eternal life revolves. It is conducive to everlasting glory; it is the cause of the exultation of the world of humanity. Again His Holiness Christ says, "Whosoever has not received a portion of the spirit is as dead. Let the dead bury their dead." In another place Christ says, "You must be baptized with the spirit." This Spirit is the life of the world of humanity; the cause of eternal illumination. It inspires man to attain to the virtues and perfections of the divine world.
May each one of you become the recipient of the Spirit. This is my hope.
(‘Abdu’l-Baha, a talk given on January 30, 1913, at 30 rue St. Didier Paris; from Persian notes, translated by Ahmad Sohrab; Star of the West, vol. IV, no. 2, April 9, 1913)