The difference between human beings and animals, is that we are given a will to transcend nature, which we come to recognize by seeing our opposition to it.
In other words, the more we evolve, the more our egoism increases; when we want more, we suffer more. Couple this suffering with the recognition caused by our innate nature, and we humans are given a place for free choice: We can voluntarily welcome ourselves into the laws of nature – something animals have no option of doing. Realizing our opposition to nature’s laws and working toward them will bring unprecedented collective spiritual consciousness in our earthly existence:
If nature’s laws were disclosed, we would be like animals. But since these laws are hidden, it enables us to reach the spiritual degrees. For the time being, we are neither one nor the other. We are more afflicted than animals, we suffer more than animals can ever suffer, and it is because we haven’t reached the spiritual level.
http://www.youtube.com/watch?v=tBj4Ny19vfQ