But in the estimation of the divine philosophers this proof and assurance is not reliable; nay, rather, they deem the standard of the senses to be false because it is imperfect. Sight, for instance, is one of the most important of the senses, yet it is subject to many aberrations and inaccuracies. The eye sees the mirage as a body of water; it regards images in the mirror as realities when they are but reflections. A man sailing upon the river imagines that objects upon the shore are moving, whereas he is in motion, and they are stationary. To the eye the earth appears fixed, while the sun and stars revolve about it. As a matter of fact, the heavenly orbs are stationary, and the earth is turning upon its axis. The colossal suns, planets and constellations which shine in the heavens appear small, nay, infinitesimal to human vision, whereas in reality they are vastly greater than the earth in dimension and volume. A whirling spark appears to the sight as a circle of fire. There are numberless instances of this kind which show the error and inaccuracy of the senses. Therefore, the divine philosophers have considered this standard of judgment to be defective and unreliable.
(‘Abdu’l-Bahá, The Promulgation of Universal Peace, p. 253-254)
In man five outer powers exist, which are the agents of perception, that is to say, through these five powers man perceives material beings. These are sight, which perceives visible forms; hearing, which perceives audible sounds; smell, which perceives odors; taste, which perceives foods; and feeling, which is in all parts of the body, and perceives tangible things. These five powers perceive outward existences.
(‘Abdu’l-Bahá, Bahá’í World Faith, p. 317)
The criterion of the senses is not reliable. For instance, consider a mirror and the images reflected in it. These images have no actual corporeal existence. Yet if you had never seen a mirror, you would firmly insist and believe that they were real. The eye sees a mirage upon the desert as a lake of water, but there is no reality in it. As we stand upon the deck of a steamer, the shore appears to be moving, yet we know the land is stationary and we are moving. The earth was believed to be fixed and the sun revolving about it, but although this appears to be so, the reverse is now known to be true. A whirling torch makes a circle of fire appear before the eye, yet we realize there is but one point of light. We behold a shadow moving upon the ground, but it has no material existence, no substance. In deserts the atmospheric effects are particularly productive of illusions which deceive the eye. Once I saw a mirage in which a whole caravan appeared traveling upward into the sky. In the far North other deceptive phenomena appear and baffle human vision. Sometimes three or four suns, called by scientists mock suns, will be shining at the same time, whereas we know that the great solar orb is one and that it remains fixed and single. In brief, the senses are continually deceived, and we are unable to separate that which is reality from that which is not.
(‘Abdu’l-Bahá, The Promulgation of Universal Peace, p. 20)
The eye is the organ of sense by which we view the world of outer phenomena; hearing is the faculty for distinguishing sounds; taste senses the properties of objects, such as bitter, sweet; smell detects and differentiates odors; touch reveals attributes of matter and perfects our communication with the outer world; yet after all, the circle and range of perception by the five senses is exceedingly limited. But the intellectual faculty of man is unlimited in its sphere of action. The eye views details perhaps a mile, but the intellect can perceive the far East and West. The ear may hear tone modulations at one thousand feet, but the mind of man can detect the harmonies of the heavenly spheres as they swing in their courses.
(‘Abdu’l-Bahá, The Promulgation of Universal Peace, p. 63-64)
For example, the being of man must unite all perfections to be perfect. Sight is extremely precious and appreciated, but it must be aided by hearing; the hearing is much appreciated, but it must be aided by the power of speech; the faculty of speech is very acceptable, but it must be aided by the power of reason, and so forth.
(‘Abdu’l-Bahá, Some Answered Questions, p. 302)