There are several reasons why a person’s central goal is learning Torah:
1. Since speech is primarily not physical, its affect on the spiritual side of Man is very powerful.
2. The holiness of the Torah affects even physical things. When a person tans an animal hide and writes a Sefer Torah on it, the leather parchment itself becomes inherently holy. Even more so when a person prepares himself to learn Torah, and says the appropriate blessing, his brain becomes no less holy than the Torah parchment. If an animal can become holy by pronouncing it an offering, surely the human being who dedicates himself to saying words of Torah becomes much more holy than an animal offering.
