In this week's Torah portion Moses reviews the laws of Kosher. Which animals are permitted to be eaten and which aren't.
Ramban, one of the great Jewish scholars from the middle ages, says that although the commandments are first and foremost an expression of G-d's Will, which by its very concept would be beyond human comprehension, yet, there are benefits in the Mitzvot that our rational human minds can also appreciate.
"We are what we eat," goes the popular saying. Now, this is not only true physically, but spiritually as well. Since the non-kosher animals have more aggressive natures and are usually carnivorous, when we eat them, says the Ramban, we are absorbing some of their physical and spiritual energy, and thus something of their traits.
Thus, avoiding eating non-kosher, is not only about fulfilling G-d's Will, but also a means to help us ensure that our spiritual antenna, our natural sensitivity to holiness and spiritual things, remains uncluttered and in optimum condition.