These are Vedic instructions. One must have full faith in the words of the spiritual master and similar faith in the Supreme Personality of Godhead. Then the real knowledge of ātmā and Paramātmā and the distinction between matter and spirit will be automatically revealed. This ātma-tattva, or spiritual knowledge, will be revealed within the core of a devotee's heart because of his having taken shelter of the lotus feet of a mahājana such as Prahlāda Mahārāja.6.23]: yasya deve parā bhaktir yathā deve tathā gurau tasyaite kathitā hy arthāḥ prakāśante mahātmanaḥ"Only unto those great souls who have implicit faith in both the Lord and the spiritual master are all the imports of Vedic knowledge automatically revealed." In the Chāndogya Upaniṣad it is said, ācāryavān puruṣo veda: "One who approaches a bona fide spiritual master can understand everything about spiritual realization."