Organisms are organized both internally and externally. The centrality of the organism in examination of the hierarchy of biological organization and the kinds of “emergent properties” that develop from study of organization at one level relative to other levels are my themes. That centrality has not often been implicit in discussion of unifying concepts, even evolution. Few general or unifying principles integrate information derived from various levels of biological organization. However, as the genetic toolbox and other new techniques are now (...) facilitating broader views of organisms and their internal and external interactions, and their evolution, some fundamental perspectives are emerging for many kinds of studies of biology. In particular, more hierarchical approaches are gaining favor in several areas of biology. Such approaches virtually demand the integration of data and theory from different levels of study. They require explicit delineations of methodology and clear definition of terms so that communication per se among scientists can become more integrative. In so doing, a hierarchy of theory will develop that demands ever further integration, potentially leading to unifying concepts and a general theory for biology. (shrink)