The first line of a verse in the Kathopanishada underscores the importance of the mind. The first part of the line runs like this: Indriyebhya: para Hyartha. It means something to the effect: the Arthas, which means the objects of the organs of the body, is greater than the Indriyas, the organs. What are the objects of the organs? Shabnam, sound, is the object of the ear. Rupam, form, is the object of the eye. Sparsham, touch, is the object of the skin.
Rasam, taste, is the object of the tongue. Gandham, smell, is the object of the nose. These five objects are also known as the Visayas. The present part of the line says that the Visayas are greater than the Indriyas. Why? In his comments upon the verse, Adi Shankaracharya says that it is because the Visayas are subtler than the Indriyas, which is true. Anyone can see the organs, but barring Rupam and Sparsham, the Visayas can not be seen. So they are certainly subtler than the Indriyas.
The second reason that Adi Shankaracharya cites is that they are more Pratyagamatmakam than the Indriyas. The word Pratyagamatma means the soul of an individual and so the word Paratyagamatkam means something that is related to the soul. The organs can not know anything on their own, they often need the help of the mind or the intelligence to know that thing. So they can not have any kind of knowledge, far less the knowledge of the soul.
In the case of the eye reading a spiritual book, it is the book that knows the soul better than the eye that reads it, it is the book that is more related to the soul than the eye. In the case of the ear listening to a spiritual sermon, it is the sermon that is more related to the soul than the ear that listens. In this sense, Adi Shankaracharya says that the Visayas are more related to the soul than the Indriyas.
The next part of the line is Arthebhyashch param mana: It means something to the effect that the mind is greater than the Visayas. Why? One reason cited by Adi Shankaracharya is that the mind is subtler than the Visayas, which is very true. Rupam or Sparsham can be seen but no one can see the mind. Gandham can be smelled but no one can smell the mind. Shabnam can be heard but no one can hear the mind.
Rasam can be tasted but no one can taste the mind. So the mind is certainly subtler than the Visayas. Another reason cited by Adi Shankaracharya is that the mind is more Pratyagamatmakam than the Visayas. The mind can know the soul better than the Visayas.
So it is more related to the soul than the Vishayas. Even if the mind is yet to know the soul, it can get firmly resolved to know it through spiritual sadhana. Adi Shankaracharya rightly observes in his comments on the verse that the mind is the birthplace of things like Sankalpa, a firm resolve, and Vikalpa, a doubt. He is trying to say that the mind can get resolved to know the soul and the mind can also have doubts about the same.
The resolving mind is certainly greater than the doubting one. So what Adi Shankaracharya suggests here is that the mind is greater than the Visayas but we can make it greater by making it firmly resolved to know the soul. Let us acknowledge this importance of the mind and try to make it greater in the way suggested by Adi Shankaracharya.