The impersonalists think that, "I am one with the Supreme. Now, due to my ignorance, I have forgotten that I am the Supreme." Because they do not recognize the Supreme Personality of Godhead, so they think that impersonal conception of the spirit soul, "I am now . . . out of ignorance, I am thinking matter, but as soon as my ignorance is over, I shall become one with the Supreme."
So this is the theory of the impersonalist. But they . . . they cannot give any answer that, "Why you have become under the influence of ignorance? If you are the Supreme, then what is the cause that you have become conditioned? Then the Supreme . . . it become conditioned under the material nature. Then how one can become the Supreme? Supreme cannot be conditioned."
So there is no answer for this question from the impersonalists' school. But real fact is that the Supreme never falls down. The part and parcel of the Supreme, they fall down—some of them—not all. So therefore the living entities, they are different from the Supreme. They are one in quality with the Supreme, but not in quantity.
So Lord Caitanya says that, "Simply by thinking that 'I am not this matter; I am spirit soul, ahaṁ brahmāsmi, I am Brahman,' that will not help you to get liberation." The real fact is that the individual living entities, they are part and parcel of the Supreme, but somehow or other, they wanted separation from the Supreme and wanted to lord it over the material nature.