  Fritz Gesztesy's varied and prolific career has produced many
transformational contributions to the spectral theory of one-dimensional
Schr\"odinger equations. He has often done this by revisiting the insights of
great mathematical analysts of the past, connecting them in new ways, and
reinventing them in a thoroughly modern context.
  In this short note we recall and relate some classic transformations that
figure among Fritz Gestesy's favorite tools of spectral theory, and indeed
thereby make connections among some of his favorite scholars of the past, Bohl,
Darboux, and Green. After doing this in the context of one-dimensional
Schr\"odinger equations on the line, we obtain some novel analogues for
discrete one-dimensional Schr\"odinger equations. \smallskip
  Dem einzigartigen Fritz gewidmet.
