We are at the midpoint in the "Decade of the Brain". Why do we know so much and yet understand so little about the brain? The field of neuroscience has exploded, and anyone who attends one of the large meetings has the impression of drinking from a fire hydran- as so aptly put by the late neuroanatomist Walle J. H. Nauta. Part of that feeling is a general-information problem, experienced in other fields of scienc as well. In brain research, however, the problem is accentuated by the rapid advances of molecular and cellular brain research. The dynamics created by these lines of research have multiplied published output, but have inevitably entailed a compartmentalization of scientific interests and research strategies. If the cost of gaining knowledge is a shrinking horizon of the individual scientist, neuroscience must develop strategies for organizing the acquisition of knowledge. Some of this guidance is given by the society -by medical and, perhaps, commercial needs. But who provides the backbone for establishing a generally accepted "schema" for basic brain research -a frame of reference onto which the millions of information fragments can be fitted, in a way acceptable to a multicultural and polymethodical neuroscience community? We believe that developmental and evolutionary biology has the potential to provide a commonly accepted frame of reference for that multilevel system approach needed to understand the workings of the brain.