While initially a fact of the developed world, the pace of similar graying is accelerating even more rapidly in the Second and Third Worlds. This gray delta constitutes about 35 million living Americans, who may use one-half or more of the health care resources. A would have to be a lot more foolish than B if they failed to recognize that in the coming decade the causation, case-mix, and area of the gray delta demands a change from early, mid-or even later-century medicine. If Homer Smith was right in saying, "We are what we are because we have the kind of kidneys we have" and "The kidneys make the stuff of philosophy", then the who, what, where, when, and why the gray delta will be cared for must focus on the stuff of geriatric nephrology.