In the Brahma-saṁhitā a nice description of the sound of Kṛṣṇa's flute is given: "When Kṛṣṇa began to play on His flute, the sound vibration entered into the ear of Brahmā as the Vedic mantra oṁ." This oṁ is composed of three letters—A, U, and M—and it describes our relationship with the Supreme Lord, our activities by which we can achieve the highest perfection of love and the actual position of love on the spiritual platform. When the sound vibration of Kṛṣṇa's flute is expressed through the mouth of Brahmā, it becomes Gāyatrī. Thus by being influenced by the sound vibration of Kṛṣṇa's flute, Brahmā, the supreme creature and first living entity of this material world, was initiated as a brāhmaṇa. That Brahmā was initiated as a brāhmaṇa by the flute of Kṛṣṇa is confirmed by Śrīla Jīva Gosvāmī. When Brahmā was enlightened by the Gāyatrīmantra through Kṛṣṇa's flute, he attained all Vedic knowledge. Acknowledging the benediction offered to him by Kṛṣṇa, he became the original spiritual master of all living entities.
The word klīm added to the Gāyatrīmantra is explained in the Brahma-saṁhitā as the transcendental seed of love of Godhead, or the seed of the Kāma-gāyatrī. The object is Kṛṣṇa, who is the ever green Cupid, and by utterance of klīm Kṛṣṇa is worshiped. It is also stated in the Gopāla-tāpanī Upaniṣad that when Kṛṣṇa is spoken of as Cupid one should not think of Him as the Cupid of this material world. As already explained, Vṛndāvana is the spiritual abode of Kṛṣṇa, and thus the word Cupid is also spiritual and transcendental when applied to Kṛṣṇa. One should not take the material Cupid and Kṛṣṇa to be on the same level. The material Cupid increases the attraction of the external flesh and body, but the spiritual Cupid increases the attraction the Supersoul exerts upon the individual soul. Actually, lust and the sex urge are there in spiritual life, but when the spirit soul is embodied in material elements, that spiritual urge is expressed through the material body and is therefore pervertedly reflected. One who actually becomes conversant with the science of Kṛṣṇa consciousness can understand that his material desire for sex is abominable whereas spiritual sex is desirable.
Spiritual sex is of two kinds: one in accordance with the constitutional position of the self, and the other in accordance with the object. When one understands the truth about this life but is not completely cleansed of material contamination, he is not factually situated in the transcendental abode, Vṛndāvana, although he may understand spiritual life. In this stage he can utter the Kāma-gāyatrī with the kāma-bīja. When, however, he becomes free from all bodily sex urges, he can actually attain the supreme abode of Vṛndāvana.