In Judaism there has existed an idea concerning eating and drinking and everything that is done, that certain things are allowed and certain things forbidden, and the same ideas were perhaps developed a little more in Islam. Those who have followed them have obeyed the law of religion, and those who have understood them have found the truth. Of edible things, flesh in particular, the flesh of certain beasts and birds and of certain creatures living in the water was forbidden. The only reason underlying this law was the protection of man against eating anything that he might like, which may perhaps hinder his spiritual evolution.