SB 4.8.45
prasanna-vadanekṣaṇam
sunāsaṁ subhruvaṁ cāru-
kapolaṁ sura-sundaram
This verse clearly explains how one has to meditate on the form of the Lord. Impersonal meditation is a bogus invention of modern days. In none of the Vedic literatures is impersonal meditation recommended. In Bhagavad-gītā, when meditation is recommended, the word mat-paraḥ, which means “pertaining to Me,” is used. Any Viṣṇu form pertains to Lord Kṛṣṇa because Lord Kṛṣṇa is the original Viṣṇu form. Sometimes someone tries to meditate upon the impersonal Brahman, which is described in Bhagavad-gītā as avyakta, meaning “unmanifested” or “impersonal.” But it is remarked by the Lord Himself that those who are attached to this impersonal feature of the Lord suffer a very troublesome task because no one can concentrate on the impersonal feature. One has to concentrate on the form of the Lord, which is described here in connection with Dhruva Mahārāja’s meditation. As will be apparent from later descriptions, Dhruva Mahārāja perfected this kind of meditation, and his yoga was successful.
