First and foremost among these favors, which the Almighty hath conferred upon man, is the gift of understanding. His purpose in conferring such a gift is none other except to enable His creature to know and recognize the one true God – exalted be His glory. This gift giveth man the power to discern the truth in all things, leadeth him to that which is right, and helpeth him to discover the secrets of creation.
(Baha’u’llah: Gleanings, p. 194)

God has bestowed the gift of mind upon man in order that he may weigh every fact or truth presented to him and adjudge whether it be reasonable. That which conforms to his reason he may accept as true, while that which reason and science cannot sanction may be discarded as imagination and superstition, as a phantom and not reality.
(`Abdu’l-Baha: Promulgation of Universal Peace, p. 374)

God gave this power to man that it might be used for the advancement of civilization, for the good of humanity, to increase love and concord and peace.
(`Abdu’l-Baha: Paris Talks, p. 42)

Powers and Actions:
The understanding is the power by which man acquires his knowledge of the several kingdoms of creation, and of various stages of existence, as well as of much which is invisible.
Possessing this gift, he is, in himself, the sum of earlier creations – he is able to get into touch with those kingdoms; and by this gift, he can frequently, through his scientific knowledge, reach out with prophetic vision.
Intellect is, in truth, the most precious gift bestowed upon man by the Divine Bounty. Man alone, among created beings, has this wonderful power.
All creation, preceding Man, is bound by the stern law of nature. The great sun, the multitudes of stars, the oceans and seas, the mountains, the rivers, the trees, and all animals, great or small – none is able to evade obedience to nature’s law.
Man alone has freedom, and, by his understanding or intellect, has been able to gain control of and adapt some of those natural laws to his own needs. By the power of his intellect he has discovered means by which he not only traverses great continents in express trains and crosses vast oceans in ships, but, like the fish he travels under water in submarines, and, imitating the birds, he flies through the air in airships.
Man has succeeded in using electricity in several ways – for light, for motive power, for sending messages from one end of the earth to the other – and by electricity he can even hear a voice many miles away!
By this gift of understanding or intellect he has also been able to use the rays of the sun to picture people and things, and even to capture the form of distant heavenly bodies.
We perceive in what numerous ways man has been able to bend the powers of nature to his will.
(`Abdu’l-Baha: Paris Talks, pp. 41-42)

Baha’u’llah says there is a sign (from God) in every phenomenon: the sign of the intellect is contemplation and the sign of contemplation is silence, because it is impossible for a man to do two things at one time – he cannot both speak and meditate.
It is an axiomatic fact that while you meditate you are speaking with your own spirit. In that state of mind you put certain questions to your spirit and the spirit answers: the light breaks forth and the reality is revealed.
(`Abdu’l-Baha: Paris Talks, p. 174)

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. Mind makes geological discoveries in subterranean depths and determines the processes of creation in the earth’s lowest strata. The sciences and arts, all inventions, crafts, trades and their products have come forth from the intellect of man. It is evident that within the human organism the intellect occupies the supreme station.
(`Abdu’l-Baha: Promulgation of Universal Peace, pp. 63-64)

According to the limitations of his physical powers man was intended by creation to live upon the earth, but through the exercise of his mental faculties, he removes the restriction of this law and soars in the air like a bird. He penetrates the secrets of the sea in submarines and builds fleets to sail at will over the ocean’s surface, commanding the laws of nature to do his will. All the sciences and arts we now enjoy and utilize were once mysteries, and according to the mandates of nature should have remained hidden and latent, but the human intellect has broken through the laws surrounding them and discovered the underlying realities. The mind of man has taken these mysteries out of the plane of invisibility and brought them into the plane of the known and visible.
(`Abdu’l-Baha: Promulgation of Universal Peace, p. 351)

All blessings are divine in origin, but none can be compared with this power of intellectual investigation and research, which is an eternal gift producing fruits of unending delight. Man is ever partaking of these fruits. All other blessings are temporary; this is an everlasting possession. Even sovereignty has its limitations and overthrow; this is a kingship and dominion which none may usurp or destroy. Briefly, it is an eternal blessing and divine bestowal, the supreme gift of God to man. Therefore, you should put forward your most earnest efforts toward the acquisition of science and arts. The greater your attainment, the higher your standard in the divine purpose. The man of science is perceiving and endowed with vision, whereas he who is ignorant and neglectful of this development is blind. The investigating mind is attentive, alive; the callous and indifferent mind is deaf and dead. A scientific man is a true index and representative of humanity, for through processes of inductive reasoning and research he is informed of all that appertains to humanity, its status, conditions and happenings. He studies the human body politic, understands social problems and weaves the web and texture of civilization. In fact, science may be likened to a mirror wherein the infinite forms and images of existing things are revealed and reflected. It is the very foundation of all individual and national development. Without this basis of investigation, development is impossible. Therefore, seek with diligent endeavor the knowledge and attainment of all that lies within the power of this wonderful bestowal.
(`Abdu’l-Baha: Promulgation of Universal Peace, p. 50)

The power of the intellect is one of God’s greatest gifts to men, it is the power that makes him a higher creature than the animal. For whereas, century by century and age by age man’s intelligence grows and becomes keener, that of the animal remains the same.
(`Abdu’l-Baha: Paris Talks, p. 72)

Knowledge is of two kinds. One is subjective and the other objective knowledge – that is to say, an intuitive knowledge and a knowledge derived from perception.
The knowledge of things which men universally have is gained by reflection or by evidence – that is to say, either by the power of the mind the conception of an object is formed, or from beholding an object the form is produced in the mirror of the heart. The circle of this knowledge is very limited because it depends upon effort and attainment.
But the second sort of knowledge, which is the knowledge of being, is intuitive; it is like the cognizance and consciousness that man has of himself.
For example, the mind and the spirit of man are cognizant of the conditions and states of the members and component parts of the body, and are aware of all the physical sensations; in the same way, they are aware of their power, of their feelings, and of their spiritual conditions. This is the knowledge of being which man realizes and perceives, for the spirit surrounds the body and is aware of its sensations and powers. This knowledge is not the outcome of effort and study. It is an existing thing; it is an absolute gift.
(`Abdu’l-Baha: Some Answered Questions, p. 157)

There are certain pillars which have been established as the unshakeable supports of the Faith of God. The mightiest of these is learning and the use of the mind, the expansion of consciousness, and insight into the realities of the universe and the hidden mysteries of Almighty God.
(`Abdu’l-Baha: Selections … `Abdu’l-Baha, p. 126)

Soul, Spirit, and Mind:
But the mind is the power of the human spirit. Spirit is the lamp; mind is the light which shines from the lamp. Spirit is the tree, and the mind is the fruit. Mind is the perfection of the spirit and is its essential quality, as the sun’s rays are the essential necessity of the sun.
(`Abdu’l-Baha: Some Answered Questions, p. 209)

Now concerning mental faculties, they are in truth of the inherent properties of the soul, even as the radiation of light is the essential property of the sun. The rays of the sun are renewed but the sun itself is ever the same and unchanged. Consider how the human intellect develops and weakens, and may at times come to naught, whereas the soul changeth not. For the mind to manifest itself, the human body must be whole; and a sound mind cannot be but in a sound body, whereas the soul dependeth not upon the body. It is through the power of the soul that the mind comprehendeth, imagineth and exerteth its influence, whilst the soul is a power that is free. The mind comprehendeth the abstract by the aid of the concrete, but the soul hath limitless manifestations of its own. The mind is circumscribed, the soul limitless. It is by the aid of such senses as those of sight, hearing, taste, smell and touch, that the mind comprehendeth, whereas the soul is free from all agencies.
(`Abdu’l-Baha: Tablet to August Forel, p.8)

When man allows the spirit, through his soul, to enlighten his understanding, then does he contain all Creation; because man, being the culmination of all that went before and thus superior to all previous evolutions, contains all the lower world within himself. Illumined by the spirit through the instrumentality of the soul, man’s radiant intelligence makes him the crowning-point of Creation.
(`Abdu’l-Baha: Paris Talks, pp. 96-97)

What the Baha’is do believe though is that we have three aspects of our humanness, so to speak, a body, a mind and an immortal identity – soul or spirit. We believe the mind forms a link between the soul and the body, and the two interact on each other.
(Shoghi Effendi: Arohanui: Letters to New Zealand, p. 89)

All that the sages and mystics have said or written have never exceeded, nor can they ever hope to exceed, the limitations to which man’s finite mind hath been strictly subjected. To whatever heights the mind of the most exalted of men may soar, however great the depths which the detached and understanding heart can penetrate, such mind and heart can never transcend that which is the creature of their own conceptions and the product of their own thoughts. The meditations of the profoundest thinker, the devotions of the holiest of saints, the highest expressions of praise from either human pen or tongue, are but a reflection of that which hath been created within themselves, through the revelation of the Lord, their God. Whoever pondereth this truth in his heart will readily admit that there are certain limits which no human being can possibly transgress.
(Baha’u’llah: Gleanings, pp. 317-318)

Consider the rational faculty with which God hath endowed the essence of man. Examine thine own self, and behold how thy motion and stillness, thy will and purpose, thy sight and hearing, thy sense of smell and power of speech, and whatever else is related to, or transcendeth, thy physical senses or spiritual perceptions, all proceed from, and owe their existence to, this same faculty. So closely are they related unto it, that if in less than the twinkling of an eye its relationship to the human body be severed, each and every one of these senses will cease immediately to exercise its function, and will be deprived of the power to manifest the evidences of its activity. It is indubitably clear and evident that each of these afore-mentioned instruments has depended, and will ever continue to depend, for its proper functioning on this rational faculty, which should be regarded as a sign of the revelation of Him Who is the sovereign Lord of all. Through its manifestation all these names and attributes have been revealed, and by the suspension of its action they are all destroyed and perish.
It would be wholly untrue to maintain that this faculty is the same as the power of vision, inasmuch as the power of vision is derived from it and acteth in dependence upon it. It would, likewise, be idle to contend that this faculty can be identified with the sense of hearing, as the sense of hearing receiveth from the rational faculty the requisite energy for performing its functions.
This same relationship bindeth this faculty with whatsoever hath been the recipient of these names and attributes within the human temple. These diverse names and revealed attributes have been generated through the agency of this sign of God. Immeasurably exalted is this sign, in its essence and reality, above all such names and attributes. Nay, all else besides it will, when compared with its glory, fade into utter nothingness and become a thing forgotten.
Wert thou to ponder in thine heart, from now until the end that hath no end, and with all the concentrated intelligence and understanding which the greatest minds have attained in the past or will attain in the future, this divinely ordained and subtle Reality, this sign of the revelation of the All-Abiding, All-Glorious God, thou wilt fail to comprehend its mystery or to appraise its virtue.
(Baha’u’llah: Gleanings, pp. 164-165)