In plain words
In waking you are Viśva; in dream you are Taijasa; in deep sleep you are Prājña. What does Prājña mean? That is Prajñānaṃ brahma. The Ātma principle itself is prajñā. So whatever power there is in the oneness of these four sayings is the true Guru. The Guru is the very embodiment of the essence of these four Mahāvākyas, ‘Prajñānaṃ brahma’, ‘Ahaṃ brahmasmi’, ‘Tat tvaṃ asi’, ‘Ayamātma brahma’. He is ‘tattvamasyādi lakṣyaṃ’.
God alone is ‘ekaṃ’
‘Ekaṃ’: ekamevā advitīyaṃ brahma. There is one, only one. It was there before birth, after death, and at every moment of life. It is one, and it does not change. That is, God alone is ‘ekaṃ’. No one else is ‘ekaṃ’. All the rest are made up of the many. That is, he who has recognised that the many is within the one itself is the Guru. How is this? How is the many within the one? There is a banyan seed. This banyan seed is just one. Yet in that very seed is a great tree. In that very tree are many branches. In the branches are many smaller branches. In it are flowers. In it are fruits. In it are roots. Everything is in it. Do you see! The roots are separate, the branches are separate, the flowers are separate, the leaves are separate, the fruits are separate; yet this whole great tree is contained in one single seed. ‘Ekaṃ sat viprāḥ bahudhā vadanti.’ Though what exists is one, one person calls it branches. Another calls it leaves. Another calls it fruits. Another calls it flowers. Ekaṃ is one! He who is that One is the true Guru. Who is that Guru? God Himself!
God has neither beginning nor end; He is always there and does not change
‘Nityaṃ.’ He who never changes is nitya. In no circumstance whatever does He change. Now, the sun, the moon and the rest change. They move.