Kolkata, West Bengal
We know that our primary sense organ for vision is the eye. With its help, we see. Humans and other animals have two eyes, but some animals have multiple instruments that function like eyes. Yet, at the beginning of learning, we encounter the term ‘three eyes.’ That is, the number of eyes is three. We see two eyes in front of us, but we are learning about three eyes—how does that make sense?
The meaning of this has become clearer later when I understood that seeing through the eyes is effective only when the mind is engaged. If the mind is distracted, we cannot even ‘see’ what is happening in front of our eyes. In other words, light entering through the eyes does not create any feeling in the brain. Therefore, it can be said that the eye alone is not a complete instrument; it needs the mind’s help. Based on this, I would say that when the mind has knowledge about a subject, the way of seeing changes. For example, imagine clothes hanging on an aluminum wire in a courtyard and similar wires hanging on a cement pole by the road. To the two eyes through which we see, the wires appear the same. But someone with knowledge of electricity would not view the two wires as identical. The wire in the courtyard can be touched, but the wire on the cement pole cannot be touched. Here, the knowledge of electricity is performing the work of a type of eye. This eye is called the eye of knowledge or the knowledge eye. That’s why it is said there are three eyes.
We can also think of the third eye in another way. Although the eye is a sensory organ, it is essentially a collector. It gathers light rays from the environment and sends them to a part of the brain called the occipital lobe. This part creates our visual perception.
Now, let’s talk about another type of eye. A blind person’s cane functions somewhat like an eye. However, this eye is not present in humans but is found in other creatures that are less advanced than humans. Animals that have received such devices from nature, in a sense, by inheritance, have something humans invented. The name of this device helps in understanding. It is called a 'radar.' It is used especially in airplanes and satellites. It generates and emits special types of electromagnetic waves. These waves travel through space or the air. If waves reflected from a certain direction return, the device can determine how far away the object is that the waves have hit. This way, unseen objects can be detected. Similarly, a radar-like device is present in the bat’s head. However, instead of electromagnetic waves, bats produce high-frequency sound waves. Our ears are incapable of perceiving these sound waves. Although this inability is a blessing from nature to us; otherwise, sleeping would be difficult. Bats can navigate in the dark thanks to their nature-given ‘radar’ device. However, the radar device needs the help of the mouth and ears. It produces sounds through the mouth and listens to the reflected sounds or echoes through the ears. When the bat makes a sound through its mouth, its ears temporarily close with the help of a muscle. If the bat’s ears are completely closed in any way, it cannot fly properly in the dark. That’s why I say a bat’s ear is a type of ‘eye.’ In this case, the bat uses its ears instead of eyes, despite having eyes. But what if an animal has no eyes at all? No, I am not talking about blind humans. I am talking about eye-less creatures like earthworms. They move around quite well, understanding their environment with the help of light-sensitive cells outside their body. These cells are considered primitive eyes of animals, from which we evolved to have our current two eyes.