Cognition is the acquisition of knowledge, or knowledge in the making. This sounds obvious as long as we do not ask what cognition and knowledge are, for we should admit that we don't know much about either. But we are getting to know something about both, particularly since the recent reorientation of the disciplines concerned with them. Indeed, neuroscientists and psychologists have learned that the study of cognition is that of certain brain processes in a social context; they also know that cognition and emotion, though distinguishable, are not separable. Furthermore, contrary to classical epistemology, which focused on the contemporary adult knowing subject, at present the study of cognition includes both its ontogeny and its phylogeny. Thus, what used to be separate disciplines have been converging.