But for those whose ignorance has been destroyed by knowledge of the Self, that knowledge, like the sun, illuminates the Supreme.

Illuminating power of knowledge. Jñānena ātmanaḥ — by knowledge of the Self — ajñānam nāśitam — ignorance destroyed — describes radical transformation.

Āditya-vat — like the sun — indicates that knowledge is self-luminous, does not depend on another light. Prakāśayati tat param — illuminates the Supreme — shows that ignorance veiled reality that was always present. One does not reach the new; one recognizes the ever-present.