The Torah is teaching us that, much like certain chemicals can affect a man’s mood, that there are some properties that have a permanent effect on the nature of man. They change his nefesh, which changes the way that he thinks and feels.
Similarly, the mefarshim explain that none of the kosher animals are predators. The nature of a predatory animal is to hunt down and kill. If a person were to consume meat from such an animal, some part of the nefesh of that animal would enter into man’s soul and he would acquire an aggressive, violent nature. The Torah forbids it because it would damage the fine balance in man.
This concept is significant as it helps us better understand the Torah as the system of human perfection. Hashem is the Creator, and He wrote the Torah as the guidebook for human growth. Contained within it are all the tools necessary to reach greatness. Some of the tools are easily understood and some take years to fully comprehend, but the system is there. By following the guidelines, restrictions, and commandments, a person guarantees that he is headed in the right path – using his stay on the planet to grow and perfect himself.