here he began rocking her back and forth , from behind him to in front of him , back and forth and then he rocked her farther back than before , almost shoulder-high , and then , with a heave and an unleashing of tension , he shot her forward and let her go , and like a little arrow she shot up and out over the cliff , suspended , it seemed , for a while high in the gray air , then she began falling and then she was gone .