He [‘Abdu’l-Baha] is… the "Mystery of God" -- an
expression by which Bahá'u'lláh Himself has chosen to designate Him, and which,
while it does not by any means justify us to assign to Him the station of
Prophethood, indicates how in the person of 'Abdu'l-Bahá the incompatible
characteristics of a human nature and superhuman knowledge and perfection have
been blended and are completely harmonized.
- Shoghi Effendi (‘The World Order
of Baha'u'llah’)