The interdisciplinary approach so popular today is more than a matter of fashion. It is, in fact, a reflection of the recognition that a good many areas once considered ade­ quately treated by one or the other of the traditional disciplines straddle the boundaries of several. Interdisciplinary research then is, by definition, a coop­ erative venture by several autonomous branches of science into areas incompletely accessible to anyone of them. By stimulating cooperation among several related disciplines, such research may serve to enrich each of them; but, on the other hand, the existence of these border areas occa­ sionally serves as Ii, pretext for postponing the solution of seemingly insurmountable problems. Brain research seems to have become such a border area of science. The fortress of classical psychology is being assaulted before our very eyes, its peripheral and even its more integral areas being invaded by physiology, morphol­ ogy, physics, and chemistry. Neurophysiology, too, has ceased to be an autonomous and self-governing field, and has come increasingly to rely on the help proffered by gen­ eral psychology, epistemology, and logic, as well as exact sciences such as mathematics and physics. These border assaults have undoubtedly been beneficial for all involved. 9 Within the traditional boundaries of their stuffy principles most classical disciplines are today facing a methodological and epistemological crisis. The breaching of their walls may at least hold out some hope of a renaissance.