what is the significance of the phrase back and back and back

The quote “back and back and back,” is significant because it is repeated with some bitter irony by Jonas. Jonas is parroting a phrase used by the Giver early in his training sessions to explain the role of a Receiver within the society. Jonas uses this phrase to illustrate the utter futility of trying to change things in such a stagnant and controlled society. Sameness is more than a way of life, it validates their very existence. Jonas thinks this society can't handle change in any form.