According to Vedic culture, learned men consider all natural products, such as food grains, fruits, flowers, and milk, to be God-sent. No one can manufacture these things in man-made factories, however scientifically advanced people may be. People can make preparations of such God-sent foodstuffs, but they cannot manufacture the natural ingredients. Spiritually cultured men, therefore, feel obliged to the Lord when they get sufficient natural foodstuffs by the grace of the Lord.
The navānna-prāśana ceremony is observed as a way of acknowledging the gifts of God. Newly collected grains would first be offered to the Lord by the villagers, either individually or collectively, and in either case all the members of the village would partake of the prasādam thus offered to the Lord. Such ceremonies make the people happy and prosperous.
We should always acknowledge the mercy of God. We should not think that we can produce ample food grains merely with the help of tractors and fertilizers. These can help us only as instruments for such production; without the sanction of the Lord there is no possibility of having grains, even if there are trucks and fertilizers.
When Lord Kṛṣṇa and Baladeva were present, the good men of Vṛndāvana realized that it was due to the presence of the Lord that their supply of food grains was sufficient. Some of the people of Vṛndāvana, including Lord Kṛṣṇa's father, Nanda Mahārāja, used to perform sacrifices to propitiate King Indra, the king of heaven, because he is the controller of rains. Without good rains, grains cannot be produced, and therefore the people would offer sacrifices to Indra. Lord Śrī Kṛṣṇa, however, stopped this age-old ceremony and advised His father to offer the same sacrifice to the Supreme Lord. His purpose was to teach that we need not satisfy the various demigods in charge of the various departments of cosmic affairs; instead we must offer sacrifices to the Supreme Lord, for the Lord is the master and all others are His servants. The famous anna-kūṭa ceremony, performed in Vṛndāvana especially and also in all other parts of India, was thus introduced by the Lord, and people still follow this path by worshiping Govardhana Hill, where the Lord used to take pleasure in tending cows. People also worship Giri Govardhana as identical with the Lord, because there is no difference between God and His paraphernalia and pastimes.