BG Chap 18 - The exclusive nature of this knowledge

These words (BG 18.65) stress that one should concentrate his mind upon Kṛṣṇa—the very form with two hands carrying a flute, the bluish boy with a beautiful face and peacock feathers in His hair. There are descriptions of Kṛṣṇa found in the Brahma-saṁhitā and other literatures. One should fix his mind on this original form of Godhead, Kṛṣṇa. By doing all these or any of these, one will attain Kṛṣṇa alone, who is with human form, the son of Devakī, and the color of a blue lotus, and not the universal form with a thousand heads, not the form of Paramātmā, the size of a thumb, not Nṛsiṁha and not Varāha.