But the human spirit, unless assisted by the spirit of faith, does not become acquainted with the divine secrets and the heavenly realities. It is like a mirror which, although clear, polished, and brilliant, is still in need of light. Until a ray of the sun reflects upon it, it cannot discover the heavenly secrets.
(‘Abdu’l-Bahá, Bahá’í World Faith, p. 316)
But the spirit of faith which is of the Kingdom consists of the all-comprehending grace and the perfect attainment and the power of sanctity and the divine effulgence from the Sun of Truth on luminous light-seeking essences from the presence of the divine Unity. And by this Spirit is the life of the spirit of man, when it is fortified thereby, as Christ saith: “That which is born of the Spirit is Spirit.” And this Spirit hath both restitution and return, inasmuch as it consists of the Light of God and the unconditioned grace. So, having regard to this state and station, Christ announced that John the Baptist was Elias, who was to come before Christ. And the likeness of this station is as that of lamps kindled: for these in respect to their glasses and oil-holders, are different, but in respect to their light, One, and in respect to their illumination, One; nay, each one is identical with the other, without imputation of plurality, or diversity or multiplicity or separateness. This is the Truth and beyond the Truth there is only error.
(‘Abdu’l-Bahá, Bahá’í World Faith, p. 370