I think we memorize the understanding. For me it also works better understanding how something works than memoryzing results. I remember in high school, in maths trigonometrics, there were a list of 20 something formulas derived from a single one. Everyboby was memorizing the whole list of formulas; i just had to memorize a simple formula and the underdtanding of how to derive the others from the fundamental one on the fly.