From these reflections it appears that memory is a basic attribute of all living things, by which patterns of sensitivity and response, both inborn and acquired, are retained and progressively modified under the impact of experience. Memory is thus indispensable in all behavior, making it at once consistent and modifiable. A consideration of some of the classical psychologic features of memory indicates the extent to which it involves multimodal processes and hence extremely widespread cerebral areas. In the higher animals and in man therefore, memory can have no precise localization and thus cannot be said to "reside" in the temporal lobe or in any other restricted area. In the simplest organisms memory seems to be dependent upon modifiable molecular structure; its mechanism in a nervous system is a most elusive function of neuronal networks by which topographic and sequential patterns of stimuli sensitize the network to subsequent stimuli in the same patterns, probably through the device of summation in reverberating circuits rather than by the facilitation of anatomical pathways. Sketchy and hypothetical though our present knowledge is, this dynamic approach to the physiology of memory promises much for our understanding of the behavior of living things.Abstract Teaser