The Self, smaller than small, greater than great, is hidden in the heart of that creature. A man who is free from desires and free from grief, sees the majesty of the Self by the grace of the Creator.

In plain words: The Self, your deepest being, is tinier than the tiniest thing and bigger than the biggest, and it lives hidden in the heart. A person who has let go of craving and sorrow can see its greatness, as a gift from the Creator.