Musar su Genesi 15:17

The reason all the מצות are called גזרות, "pieces," or "sections," is that they are like the souls, each one of which is a "section" of the Divine though separated from G–d Himself. Similarly then מצוות are like the egg laid by a hen that is about to be slaughtered for human consumption (compare Beitzah 2A). In other words, the commandments are an integral part of G–d though separated from Him. The word גזר is used in this way in Psalms 136,13: "Who divided the sea into pieces." We have the same meaning in Genesis 15,17, at the "covenant between the pieces, "where G–d (a pillar of fire) is described as passing between הגזרים, the pieces. We learn there what the כריתת הברית, making of the covenant between G–d and Abraham, G–d laying phylacteries, robing Himself in ציצית, studying Torah, etc., is all about. All these activities which our sages attribute to G–d are not merely symbolisms, but reflect the fact that we, our souls, are part of the Divine, and that what we are asked to do in this physical world is basically no different from what G–d does in the spiritual counterpart of our world. It is wrong to attribute the legislation of chasing away the mother-bird to considerations involving the welfare of the bird. What G–d wishes to teach us by means of the מצות, is something for our sake, something that makes it easier for us to operate on His "wavelength." We are to train ourselves to wear "His garments," to adopt His attributes. It is not surprising then that these גזרות are difficult to understand, and the same applies to the restrictive ordinances, גזרות, imposed by Rabbinic law which are designed to prevent our infringing Sinaitic law. We sometimes fail to see the rationale in some of these ordinances.