In plain words
Our ancients, pure of heart, saw unity in diversity. But under the sway of Kali, man today has no taste at all for unity; he longs for diversity alone.
Bhūtākāśa, cittākāśa, cidākāśa
Vedānta teaches that there are three kinds of ākāśa in man. The first is bhūtākāśa, the second cittākāśa, the third cidākāśa. Bhūtākāśa belongs to the body. Whatever is made up of the seen is bhūtākāśa itself. All the sights the eye sees undergo change. Some day or other they vanish. This whole world, made up of substances, of living beings and of the five elements, is bhūtākāśa itself. Rivers, forests, mountains, the sun, the moon and the rest, the Milky Way ... All these are parts of bhūtākāśa. Cittākāśa swallows this vast bhūtākāśa. That means you may imagine how much vaster still cittākāśa is. Bhūtākāśa, so vast and so mighty, looks very small within cittākāśa. The whole world made up of the seen is held within cittākāśa as a mere atom. You may doubt how this is possible. You have seen huge mountains; you have seen great oceans; you see the sun, the moon and the stars, many crores of miles away. All these have stayed in your citta, each as small as an atom, have they not? They have likened the body to bhūtākāśa and the mind to cittākāśa. The basis of these two is cidākāśa. Bhūtākāśa: the body; cittākāśa: the mind; cidākāśa: the Ātma. Humanness is nothing other than these three blended together.
Man says, “This is my body, my mind.” So he himself is apart from these. He is of the very form of the Ātma, the one who is master of everything. To think of such a man as small is ignorance. Man is not small; his form is infinite. But you think that humanness is something very small. “The Ātma cannot be seen!” you say. The Ātma has no form of its own. It does not exist at one time and vanish at another.