Why Aren’t Humans Allowed To Follow Nature

“Among the many animals and birds, some are vegetarian and others are carnivorous, but none of them transgress the laws of nature, which have been ordained by the will of the Lord. Animals, birds, reptiles and other lower life forms strictly adhere to the laws of nature; therefore there is no question of sin for them, nor are the Vedic instructions meant for them. Human life alone is a life of responsibility.” (Shrila Prabhupada, Shri Ishopanishad, 1 Purport)