Sri Chinmoy: Atman is the soul and paramatman is the Self. When Shankara speaks about the paramatman, he means the great Self, the Self without a second, which is beyond the entire universe. Atman is the small self, the individual soul. The small self, the individual soul, is part and parcel of the paramatman. Nothing can exist apart from the paramatman. Let us say that paramatman or brahman is like the ocean. If you enter the water at any one place, you are entering into the ocean itself. You will not say that you have entered into only one tiny part of the ocean.
So if you know yourself, if you know what you are, if you live perpetually in the soul, then immediately you become consciously aware of God and of your inner existence. If you know what you are, only then can you know about the Source; if you know the soul, atman, only then can you know the source of atman, which is paramatman. They are one. If you know the son well, then through the son you can know the father. And similarly, if you know the father well, then you can know the son. If you live a divine life and enter into your own soul, which is the representative of the Absolute, then naturally you will come to know paramatman and brahman.