Gratitude

SB 3.5.49, Purport: 

The jungle animals are also maintained by the Lord with their respective foodstuffs, but they are not advanced in God consciousness. Similarly, human beings are provided with food grains, vegetables, fruits and milk by the grace of the Lord, but it is the duty of human beings to acknowledge the mercy of the Lord. As a matter of gratitude, they should feel obliged to the Lord for their supply of foodstuff, and they must first offer Him food in sacrifice and then partake of the remnants.