Whenever you meet a person, look at his figure carefully from top to bottom, and note mentally his peculiar features, condition of his eyes and eyebrows, teeth, arms, etc., the sort of dress he is wearing, whether he has got moustache or not, the kind of cap he has on his head, his voice, his behaviour, his looks, his gait, whether he seems to be a kind-hearted or cruel man, whether he is intelligent or dull, whether he is polite or not, his colour, etc. There are many people who are not able to give a clear description of the faces of their own friends with whom they are moving for years and years. The son is unable to describe exactly the physiognomy or marks on the face of his father, though he lives with him in close contact for a number of years. The obvious reason is that the son has not developed the power of memory. One cannot become a skilful scientist unless he has an acute power of observation. He has to observe the various phenomena of nature and to draw his own conclusions and inferences. He has to collect facts and figures to study the 'Law of Nature'. Enter the drawing room of your friend and notice carefully what all things you find therein. Then close your eyes and reflect. Then come out of the room and note mentally, in order, all the things which the room contains, and then enter again into the room for verification. You should practise this for some months. Then you will develop a wonderful power of sight.
Go to a library and note carefully all the books that are arranged in any two rows of the almirah or shelf. Close your eyes and reflect. Note down in your diary, and then verify. Let there be mistakes. It does not matter much. A time will come when you will not commit even a single mistake. You should be able to pick out or single out your comrade in a big crowd by noticing the nature of his gait and movements of his limbs or hands at a distance.
There was a blind man in Srinagar who could tell the nature of colours by simply feeling the cloth. What a wonderful development of the power of touch he had! It is all a matter of training. At night, you cannot see properly; the power of seeing becomes dull, but the power of hearing is intensified. This is compensation in nature. There are some deaf and dumb people in the world who are intelligent. They do good work in the press as compositors. When one organ becomes deficient, another organ gets more developed. The energy of the organ that is not in use is utilised by the other organ and it grows rapidly. Nature is very merciful and intelligent. There are some people who cannot remember more than two things at a time. There was a soldier who could not remember the ingredients of gunpowder, even though he was trained to remember for months together. This is due to ill-development of the faculty of memory.
A judge in a court of law should have an acute hearing. Then alone he will become a distinguished and able judge. Then alone he can write down quickly all evidences without any mistake. A commander-in-chief should have an acute sight. Then alone he can survey all the infantries and cavalries. Then, and then alone, he can have a clear vision of the enemies on the opposite side, even at a very long distance. One will have to develop the power of hearing and power of attention. The development of these two organs is of great help in the practice of memory-culture. In some, the organ of hearing is more developed. In others, the power of sight is more developed. Dogs have got an acute nose. They have to smell things before they get their daily bread. Prakriti has shown marked intelligence in the creation of beings. Cobras have an acute sense of hearing. They hear through their eyes. They have not got separate ears. Tigers have acute nose; they can smell blood from a very long distance. There is a play of intelligence in every inch of divine creation. Songsters and musicians have very acute hearing. They have to develop it. They will have to find out various kinds of undulations in the vibration of sounds which make difference in Ragas and Raginis. The very profession itself demands the development of the particular organ which helps them in the culture of their art or science.