Human adults experience the world as a layout of physical bodies that endure through time. Our ability to do this is both mysterious and fascinating, because the information we receive about physical objects is potentially so misleading. Consider the case of vision. Objects are bounded, but the visual scenes in which they appear are continuous arrays of surfaces. Somehow, we must determine which of the many surfaces that touch or overlap in a visual array are connected to one another. Objects are also integral units, but they are only partly visible at any given time and their visible surfaces are often separated from one another by nearer occluding objects. Somehow, we must recover the integrity of each object from this mosaic of visible fragments. Finally, objects exist and move continuously through space and time, but they are frequently occluded and disoccluded by movements of surfaces or of the observer. Somehow, we must apprehend the continuous existence of an object from our sporadic encounters with it. Vision, moreover, appears to provide the richest information for objects. The problems of apprehending objects only seem to increase when humans explore by listening or touching.