Left: Hubble Heritage image ( http://hubblesite.org/newscenter/archive/releases/2003/28/image/a/) of the Sombrero Galaxy, NGC 4594. Right: SDSS gri color image of NGC 4762, the second-brightest S0 galaxy in the Virgo Cluster. These galaxies illustrate why bulge–disk decomposition is necessary. NGC 4594 is an Sa galaxy with B/ T = 0.93 ± 0.02 (Kormendy 2011b). Without photometric decomposition, we measure essentially only the bulge. We learn nothing about the disk. If an S0 version of this galaxy—e.g., NGC 3115—were viewed face-on, it would be difficult even to see the disk (Hamabe 1982), and whole-galaxy parameters would not measure it at all. In contrast, NGC 4762 is one of the "missing" late-type S0s: we find in this section that B/ T = 0.13 ± 0.02. Without photometric decomposition, we measure essentially only the disk. We learn nothing about the bulge. Moreover, the azimuthally averaged parameters used in F2006 are particularly difficult to interpret.