Before entering the Land of Israel, Ha-shem commanded the Jewish people: "When the L-rd, your G-d, expands your boundary... and you say, 'I will eat meat,' because your soul desires to eat meat, you may eat meat, according to every desire of your soul." (Deuteronomy 12:20)
According to one of the commentaries, this verse granted them permission to eat meat out of desire. Until that time, in the desert, it had been forbidden to eat ordi-nary meat (basar chullin); only meat that had been offered as a sacrifice on the altar could be eaten. However, from the time they entered the Land of Israel, eating ordinary meat became permitted.
The Ability to Refine
At first glance, this seems difficult to un-derstand. In the desert, the Jewish people stood on a very high spiritual level. They were not burdened with the mundane con-cerns of earning a livelihood and daily physical needs; rather, they were able to dedicate their entire existence to serving G-d. In contrast, in the Land of Israel they began living ordinary earthly lives, occu-pied with all their daily responsibilities. Why, then, was it specifically when they seemingly descended from their higher spiritual level that they were permitted to eat ordinary meat?
The explanation is that precisely in the desert they were forbidden to eat meat out of desire because they had not yet been given the ability to refine and elevate the physical world. During that period, they needed to protect themselves from the influence of the material world and its distractions. Their food itself was spiritual nourishment - the manna.
It was upon entering the Land of Israel that they received the power to refine the physical world. This was the beginning of the Jewish people's mission of birurim, refining and elevating the physical aspects of this world and transforming them into a dwelling place for the Divine Presence.
Therefore, at that point they were also given the ability to elevate even "meat of desire" to holiness. For this reason, G-d permitted it to them.
Without Blood
How can ordinary meat be elevated to holiness? The Torah continues: "How-ever, be strong not to eat the blood..." Blood represents excitement and desire. The Torah teaches: eating meat itself is permitted, but the desire and passion are forbidden. Blood is sprinkled only upon the altar meaning that enthusiasm and desire must be dedicated to holiness and the service of G-d.
What should a person do with physical desires? The Torah says: "...you shall spill it on the ground, like water." A Jew has no connection to physical desire for its own sake. When a Jew engages in worldly matters such as eating meat it must be solely for the sake of Heaven, in order to serve G-d, following the idea, "know Him in all your ways..."
The Inner Desire
When a Jew feels a desire for physical things, although this desire appears to come from the body, it comes from the soul. The soul longs to refine these mat-ters, elevate them to holiness, and reveal the Divine sparks contained within them.
Thus, the verse can be explained: "And you say, 'I will eat meat'" when you feel a desire to eat meat, know that "because your soul desires to eat meat" the desire comes from the soul, which longs to elevate the meat to holiness and to refine the Divine sparks within it.
When we relate to the physical world in this way, these desires do not cause a per-son to fall spiritually. On the contrary, we are able to elevate the world and trans-form it into a dwelling place for G-d.
(the Rebbe, Likutei Sichot, Volume 4)