 He then would relearn the list, and compare the new learning curve to the learning curve of his previous memorization of the list.The second list was generally memorized faster, and this difference between the two learning curves is what Ebbinghaus called "savings".Ebbinghaus also described the difference between involuntary and voluntary memory, the former occurring "with apparent spontaneity and without any act of the will" and the latter being brought "into consciousness by an exertion of the will".