Thus, by resting on the Sabbath, we are reminded that we are free. But in a more general sense, Shabbat frees us from our weekday concerns, from our deadlines and schedules and commitments. Of course, no discussion of Shabbat would be complete without a discussion of the work that is forbidden on Shabbat. This is another aspect of Shabbat that is grossly misunderstood by people who do not observe it. Under this definition, turning on a light would be permitted, because it does not require effort, but a rabbi would not be permitted to lead Shabbat services, because leading services is his employment.
Jewish law prohibits the former and permits the latter.
Many Americans therefore conclude that Jewish law doesn't make any sense. The problem lies not in Jewish law, but in the definition that Americans are using. Melachah generally refers to the kind of work that is creative, or that exercises control or dominion over your environment. The quintessential example of melachah is the work of creating the universe, which G-d ceased from on the seventh day. The word melachah is rarely used in scripture outside of the context of Shabbat and holiday restrictions.