The relation of repetitions for learning and for repeating English stanzas needs no amplification. These were learned by heart on the first day with less than half of the repetitions necessary for the shortest of the syllable series.
Hermann EbbinghausOften, even after years, mental states once present in consciousness return to it with apparent spontaneity and without any act of the will; that is, they are reproduced involuntarily.
Hermann EbbinghausNo matter how thoroughly a person may have learned the Greek alphabet, he will never be in a condition to repeat it backwards without further training.
Hermann Ebbinghaus