  ARPES and wide area, high resolution STM studies of a micaceous cuprate high
temperature superconductor have shown strong nanoscale gap disorder, but the
question of whether this disorder is intrinsic and necessary for HTSC, or
merely incidental to either this material, or even only its surface, appears to
be an open one. We present the case that it is merely incidental, and then
review the evidence that strong disorder is actually an essential factor in
generating this unprecedented phenomenon.
