These five big elements are sensed by us; this is also a fact of experience. Therefore, Sankhya takes into account, that all these five elements are experienced by us. There is, in other words an experiencing activity: not only the five elements exist in the world, they are objects in the world, but there is a subjective movement in us; so Prakriti just as it is objective movement, there is also a subjective movement. They can all be sensed. This sensing is done by five senses corresponding to five bhūta(s); so, according to Sankhya there are five senses by which we can sense: the sense of smell, sense of sight, sense of touch, sense of taste, and the sense of hearing. These are the five senses, which are called jñānendriya(s). They are the instruments of knowledge.
These instruments of knowledge are all of them capable of being reduced to one; these are five specialities you might say, of the basic sense. That basic sense is called manas. Manas can be translated as ‘sense–mind’: it is a ‘mind’ which ‘senses’. What is the proof that these five senses can be summed up in one sense? The proof is first that different senses give you different sensations…And if there is not one sense behind it, who will coordinate all the sensations? If only five senses were distinct from each other then we would only hear, taste, smell, etc…but we could not put them together, coordinate them together; so, there must be a coordinating sense in us which senses all: there must be a sense which at once hearing, smelling, touching, tasting, seeing, at once! We also can prove by the fact that when Manas is absent, even when the sense objects are present, they are impeding upon our senses, we cannot take cognisance of them. If a mosquito is biting me, but if I am engaged in talking to you, in whom I am interested and absorbed, I may not even recognise that there is a bite; that means that although there is sensation, but it is not sensed. Why? Because, the real sense is not attached to it. Therefore, they concluded there is a sense, which you can call sense–mind, Manas. They use the term…Indian term is manas: wherever the word Manas is used in Indian psychology, it means sense–mind.
This sense–mind is capable of distinguishing between touch, smell, hearing, very distinctly; even a child who is untaught understands the distinction between taste and hearing, and so on. The sense–mind is able to discriminate between these five activities. And because of that reason it can discriminate between all the pañca mahābhūta(s): how do you know that this is liquid and this is fire? It is because the sensations of fire and the sensations of water are different, and therefore the mind can distinguish between water and fire and air and earth and the ether.
You can see that in this subtlety, you are arriving at a notion of discrimination. The Manas is able to discriminate, and it finds in discriminating that each object tends to be itself; there is a tendency in everything in the world to remain what it is: there is something in it, in every little thing; it tends to remain what it is. It can be changed but it tends to remain what it is: the earth remains earth as much as possible and atom tries to remain an atom; a bird tries to remain a bird, everything tends to remain what it is; sense of its own individuality, its own self, its identity. This is what the Sankhya call ahaṁbhāva: the egoism, the “egoity”. There is ahaṁkāra. In every little thing in the world, there is this tendency to remain what it is: ahaṁkāra.