The animal offered in the sacrificial fire is, so to speak, destroyed, but the next moment it is given a new life by dint of the Vedic hymns chanted by the expert priest
SB Canto 2
When I was born from the abdominal lotus flower of the Lord (Mahā-viṣṇu), the great person, I had no ingredients for sacrificial performances except the bodily limbs of the great Personality of Godhead.
Lord Brahmā, the creator of the cosmic manifestation, is known as Svayambhū, or one who is born without father and mother. The general process is that a living creature is born out of the sex combination of the male father and the female mother. But Brahmā, the firstborn living being, is born out of the abdominal lotus flower of the Mahā-viṣṇu plenary expansion of Lord Kṛṣṇa. The abdominal lotus flower is part of the Lord's bodily limbs, and Brahmā is born out of the lotus flower. Therefore Lord Brahmā is also a part of the Lord's body. Brahmā, after his appearance in the gigantic hollow of the universe, saw darkness and nothing else. He felt perplexity, and from his heart he was inspired by the Lord to undergo austerity, thereby acquiring the ingredients for sacrificial performances. But there was nothing besides the two of them, namely the Personality of Mahā-viṣṇu and Brahmā himself, born of the bodily part of the Lord. For sacrificial performances many ingredients were in need, especially animals. The animal sacrifice is never meant for killing the animal, but for achieving the successful result of the sacrifice. The animal offered in the sacrificial fire is, so to speak, destroyed, but the next moment it is given a new life by dint of the Vedic hymns chanted by the expert priest. When such an expert priest is not available, the animal sacrifice in the fire of the sacrificial altar is forbidden. Thus Brahmā created even the sacrificial ingredients out of the bodily limbs of the Garbhodakaśāyī Viṣṇu, which means that the cosmic order was created by Brahmā himself. Also, nothing is created out of nothing, but everything is created from the person of the Lord. The Lord says in the Bhagavad-gītā (10.8), ahaṁ sarvasya prabhavo mattaḥ sarvaṁ pravartate. "Everything is made from My bodily limbs, and I am therefore the original source of all creations."
The impersonalists argue that there is no use in worshiping the Lord when everything is nothing but the Lord Himself. The personalist, however, worships the Lord out of a great sense of gratitude, utilizing the ingredients born out of the bodily limbs of the Lord. The fruits and flowers are available from the body of the earth, and yet mother earth is worshiped by the sensible devotee with ingredients born from the earth. Similarly, mother Ganges is worshiped by the water of the Ganges, and yet the worshiper enjoys the result of such worship. Worship of the Lord is also performed by the ingredients born from the bodily limbs of the Lord, and yet the worshiper, who is himself a part of the Lord, achieves the result of devotional service to the Lord. While the impersonalist wrongly concludes that he is the Lord himself, the personalist, out of a great gratitude, worships the Lord in devotional service, knowing perfectly well that nothing is different from the Lord. The devotee therefore endeavors to apply everything in the service of the Lord because he knows that everything is the property of the Lord and that no one can claim anything as one's own. This perfect conception of oneness helps the worshiper in being engaged in His loving service, whereas the impersonalist, being falsely puffed up, remains a nondevotee forever, without being recognized by the Lord.