But, just as the exact understanding of anatomy which modern medicine enjoys, bulks to infinitely more than any one anatomist could ever have discovered, so with ethnology. No one mind could ever observe or assemble and digest all the cultural facts that are needed. Many workers are busy, have been systematically busy for two or three generations. Though they may, now and then, enliven their toil by a scientific quarrel over this or that set of facts or interpretation, they are inherently coöperating, laboring cumulatively at a great joint enterprise. Sometimes, they divide their interests topically: one specializes on social customs, another on material arts, a third along lines of religion. But, in the main, the cultural context is so important that it has been found most productive for each investigator to try to learn everything possible about all the phases of culture of a single tribe, or, at most, of two or three tribes.