Essential is a somewhat intuitively defined word, and it means what one would think it means. Take a concrete example, say, gun ownership. A person who thought in essentials would ask what rights were involved, what principles, and what standards. A person who could not think in essentials would quote statistics on hunting and self-defense, and probably talk a lot about "practicality." If one cannot think in essentials, one cannot cull the important, underlying premises that are needed to make a decision from the details that surround it.