We are very much proud of our senses, but in reality they are practically all useless in helping us understand the goal of life. Even If we might have some material deficiencies, we should not be despondent: Life is made for getting out of the control of the senses anyway, and for understanding Krishna, who is beyond the reach of said senses.
Even if you are blind and dumb, have no fear: All you need is hearing. That is the most essential facility we have in this human form of life. While other species of life also have the same facility of hearing, they do not posses the capacity of understanding, especially philosophy or detailed instruction. A fog might be able to understand a command like "sit," but he can't understand the complex, spiritual knowledge of Vedic scriptures:
Krsna says, God says, that "All living entities are My part and parcels." This instruction can be accepted only by human beings, not the cats and dogs. Although He claims that "Every living entity is My part and parcel," the cats and dogs, they have no capacity to understand these, I mean to say, utterances of the Personality of Godhead, even he has got an ear. You are hearing; a dog may hear. But you can capture; the dog cannot capture. Due to his lower grade of body, he cannot. So in this higher grade of body, the Vedic instructions are there. Now you can make your choice.
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So our understanding of knowledge should be through the agency of the ears. Actually, all other senses are useless. If a man is sleeping, none of his senses work. If there is a a fire, the sleeping man is doomed to burn until someone comes and shouts, "wake up! there's danger!" Similarly, we are in a state of sleep; we are thinking that we are this material body. Only by hearing the Hare Krsna maha-mantra and the words of a bona-fide guru can we reawaken our transcendental consciousness and senses. These two process; known as sravanam and kirtanam in Sanksrit, are the activities of fully liberated, spiritually realized beings. It is the original activity of the soul. So at that point only will one be able to see reality; with spiritual vision. One will be able to Krishna and the spiritual world, just like Lord Brahma, who says: premanjana-cchurita-bhakti-vilocanena. "I worship Govinda, the primeval Lord, who is Syamasundara, Krsna Himself with inconceivable innumerable attributes, whom the pure devotees see in their heart of hearts with the eye of devotion tinged with the salve of love." (BS 5.38) Atheists and scientists usually challenge theists; can you show me God? But they do not have the eyes to see. Krishna says in the Bhagavad-gita: bhaktya mam abhijanati
"One can understand Me as I am, as the Supreme Personality of Godhead, only by devotional service. And when one is in full consciousness of Me by such devotion, he can enter into the kingdom of God (Bg 18.55)."
This is the actual process of seeing God, not by challenge.
If we reach that stage, there is no need of material eyes. In fact it is not a great loss even to be blind, because material eyes are an impediment to spiritual life; they are one of the ways we can become bewildered by material nature and her various allurements and become entangled in this material world:
A man who has many wives is constantly harassed by them. He is responsible for their maintenance, and thus all the ladies constantly pull him in different directions, each struggling for her self-interest. Similarly, the material senses harass the conditioned soul, pulling him in many different directions at once. On one side the tongue is pulling him to arrange tasty food; then thirst drags him to get a suitable drink. Simultaneously the sex organs clamor for satisfaction, and the sense of touch demands soft, sensuous objects. The belly harasses him until it is filled, the ears demand to hear pleasing sounds, the sense of smell hankers for pleasant aromas, and the fickle eyes clamor for pleasing sights. Thus the senses, organs and limbs, all desiring satisfaction, pull the living entity in many directions.
SB 11.9.27
These impediments offered by the material senses distract us from our real goal of life, love for Krishna. They should be controlled and understood as obstacles on the path of self-realization if let loose. This exemplified by a great acarya in the gaudiya-madhava sampradaya (although his solution to the problem is no to be imitated):
When Bilvamangala Thakura was going to Vrndavana, he was still attracted to women. One night he stayed at the house of a very rich merchant, and the merchant's wife told her husband that Bilvamangala Thakura was attracted to her. She asked her husband what to do, and the merchant simply said, "Serve him." Finally Bilvamangala Thakura came to his senses, and he thought, "These eyes are my enemies." When the beautiful woman approached him, Bilvamangala Thakura said, "Mother, please give me the pins out of your hair. I am very mad after the beauty of women. So let me pluck out my eyes." In this way, he blinded himself. Although he could not see, in Vrndavana he was supplied milk by Krsna Himself. Thus he personally realized Krsna through bhakti and wrote of his personal experience.
(TLK Vs 32)
Our material eyes are also problematic because we become proud of them and think that something is true only if we can see it, and therefore we become doubtful if someone speaks of God and the soul or the spiritual world. But this is actually a great foolishness; there are many, many things which we can't perceive with our material eyes, yet we still have great faith that they exist.
The final defect of the materialistic person is his inefficient senses. Although our eyes, for example, have the power to see, they cannot see that which is situated at a distance, nor can they see the eyelid, which is the object nearest to the eye. To our untrained eyes the sun appears to be just like a plate, and to the eyes of one who is suffering from jaundice everything appears to be yellow. Therefore we cannot rely on the knowledge acquired through such imperfect eyes. The ears are equally imperfect. We cannot hear a sound vibrated a long distance away unless we put a telephone to our ear. Similarly, if we analyze all our senses in this way, we will find them all to be imperfect. Therefore it is useless to acquire knowledge through the senses. The Vedic process is to hear from authority. In the Bhagavad-gita (4.2) the Lord says, evam parampara-praptam imam rajarsayo viduh: "The supreme science was thus received through the chain of disciplic succession, and the saintly kings understood it in that way." We have to hear not from a telephone but from an authorized person, for it is he who has real knowledge.
Adi 7.108
Therefore the real seeing is through hearing, because by hearing we can perceive things beyond the jurisdiction of our limited senses. For example; to understand the actual nature of the sun as opposed to the little yellow plate we see in the sky, if we hear from a science book, we can understand that it is actually a huge planet of fire. Therefore, the actual way to perceive Krishna, God, is by hearing from authoritative sources about him:
Therefore whenever we speak something, we quote from the Vedas, from Vedic literature, to support it. Otherwise it is useless. When you speak something and corroborate it by the quotation from the Bhagavad-gita, Srimad-Bhagavatam, Upanisads -- there are so many Vedic literatures -- then it is correct. That is the Vedic system. Not that I create knowledge by my research. What is the value of your research? Because you are imperfect, your senses are imperfect, you cannot even see properly. Even you cannot see your eyelids, so what is the value of your seeing? You cannot see something from a distant place, the nearest place. There must be some adjustment, there must be light under so many conditions you can see. Then what is the value of your eyes?
Vedic knowledge is therefore not seen; it is heard. Therefore it is called sruti. Just like actually we do not understand what is the position of different planets by seeing. But when you hear from authorities, from astrologists, from astronomers, then you can understand, "The sun is so great, bigger." That means hearing is perfect knowledge, not seeing. Therefore Vedic knowledge is received through the ear. To hear from the authorized persons, that is knowledge.
Srimad-Bhagavatam 1.3.8 – September 14, 1972, Los Angeles
And this is the process which many great saints, yogis and transcendentalists have practiced from the annals of time. They never relied on their imperfect eyes or other senses, knowing them to be incapable of understanding and perceiving that which is really worth seeing.
O my Lord, Your devotees can see You through the ears by the process of bona fide hearing, and thus their hearts become cleansed and You take Your seat there. You are so merciful to Your devotees that You manifest Yourself in the particular eternal form of transcendence in which they always think of You.
SB 3.9.11
It actually makes no sense to try and understand that which is unlimited in our limited position by the means of our limited instruments. In one sense, we are actually blind. We have almost no power of seeing at all. But by the transcendental process of controlling one's senses and hearing about the Lord from a bona-fide guru, one can actually see that which is beyond matter (or He who is beyond matter, to be more specific):
This verse is also quoted from the Stotra-ratna (13) of Yamunacarya. Everything covered by the influence of maya is within the limited boundaries of space, time and thought. Even the greatest manifestation we can conceive, the sky, also has limitations. From the authentic scriptures, however, it is evident that beyond the sky is a covering of seven layers, each ten times thicker than the one preceding it. The covering layers are vast, but with or without coverings, space is limited. Our power to think about space and time is also limited. Time is eternal; we may imagine billions and trillions of years, but that will still be an inadequate estimate of the extent of time. Our imperfect senses, therefore, cannot think of the greatness of the Supreme Personality of Godhead, nor can we bring Him within the limitations of time or our thinking power. His position is accordingly described by the word ullanghita. He is transcendental to space, time and thought; although He appears within them, He exists transcendentally. Even when the Lord's transcendental existence is disguised by space, time and thought, however, pure devotees of the Supreme Lord can see Him in His personal features beyond space, time and thought. In other words, even though the Lord is not visible to the eyes of ordinary men, those who are beyond the covering layers because of their transcendental devotional service can still see Him.
Adi 3.89
To be blind is not detrimental; quite the opposite. In fact, we are already blinded by our misconceptions, biases and limited perception. The real vision of a living entity starts through his ears, and culminates in the perfection of seeing Lord Sri Krishna face to face.