A sagely guru by the name of Berra imparted some words of wisdom that I periodically revisit: "In theory there's no difference between theory and practice, while in practice there's ." Though intended for comedic effect, it rings true (as all good comedy does).
It's easy to urge so bound up in what we believe something to be, or should be, that we mistake it for reality. The more invested one is during a theory; the closer theory and practice can appear.