In plain words
The food that is very subtle is what takes shape as the Manas. That is why the whole influence of the Manas depends on the food we eat. For this, prāṇa is most necessary. Only after the prāṇamaya comes the manomaya; only after the manomaya, the vijñānamaya; only after the vijñānamaya, the ānandamaya. Where does this prāṇa come from? Who is bringing it and providing it? Through what connection does it creep in? It is nothing of the kind. That too is the very food we take in daily life. The water we drink goes out in gross form as urine. The very subtle water itself turns into prāṇa. Food as the Manas and water as the prāṇa come together in man, and the form in which the two are joined is what becomes the vijñānamaya.
This Vijñāna does not mean only worldly, physical knowledge. This is only for the outer world, only for the gross world, only for the waking state; in the subtle states, in the inner principle of the Ātma, it is of no use at all. But taking the outer as a base, you must make the right effort to nourish the inner. Everything is within; nothing comes from anywhere outside. We must recognise the difference between the Ātma and Ahaṅkāra. This sprang from the Ātma itself. From this very Ātma thoughts set out. From this very thought speech came. All in all, speech, thought and Ahaṅkāra, these three, are one family belonging to the Ātma. So Ahaṅkāra is the son of the Ātma. The son of the Ātma is thought. Speech is the son of thought, so speech is the Ātma's grand son. Great grand son, grand son, son, father: do they not all belong to one family? In the same way, this Ahaṅkāra simply keeps coming and going. Ahaṅkāra is that which comes and goes. The principle of the Ātma is that which neither comes nor goes. So you must recognise the difference between the Ātma and Ahaṅkāra. We call Ahaṅkāra 'Ego'. This is a very wrong word. People think that Ahaṅkāra is only the Ahaṅkāra that belongs to the body. No: the delusion 'I am the body' is itself Ahaṅkāra. What comes from wealth, from caste, from qualities, from learning is not Ahaṅkāra.