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 man is essential and therefore eternal. It is a divine bounty. It is the effulgence of the Sun of Reality and therefore of greater importance than the physical body.
(‘Abdu’l-Bahá, Bahá’í World Faith, p. 262)
It is quite apparent to the seeing mind that a man’s spirit is something very different from his physical body. The spirit is changeless, indestructible. The progress and development of the soul, the joy and sorrow of the soul, are independent of the physical body. If we are caused joy or pain by a friend, if a love prove true or false, it is the soul that is affected. If our dear ones are far from us—it is the soul that grieves, and the grief or trouble of the soul may react on the body. Thus, when the spirit is fed with holy virtues, then is the body joyous; if the soul falls into sin, the body is in torment … But if the body undergoes a change, the spirit need not be touched. When you break a glass on which the sun shines, the glass is broken, but the sun still shines! If a cage containing a bird is destroyed, the bird is unharmed! If a lamp is broken, the flame can still burn bright! The same thing applies to the spirit of man. Though death destroy his body, it has no power over his spirit—this is eternal, everlasting, both birthless and deathless.
(‘Abdu’l-Bahá, Paris Talks, p. 65-66)