From the creation of the world, the snake has been a negative force in the world. He successfully persuaded Adam and Eve to eat from the Tree of Knowledge, despite G-d's warning, and since then he clothes himself in the garb of the evil inclination who tries to entice us to sin. Thus, the Torah prohibits us from eating anything that moves on its stomach, which the rabbis understand to refer to the snake. But why did the Torah use such terminology, and not just tell us explicitly what it is referring to?