Inside Picture Books - By Ellen Handler Spitz Google Book Search preview p27:
Apparently, at bedtime one evening, a little boy of eighteen months had heard Goodnight Moon five times and after the final rendition was contemplating the book as it lay open before him, its last pages revealed. These pages are the ones in which the "great green room" has grown dark and quiet and the little bunny has closed his eyes. The words read: "Goodnight noises everywhere." The small boy in question stared at the open book before him and then deliberately placed one of his feet on the left hand page and struggled to get his other foot on to the right-hand page; thereupon, he burst into tears. His mother, watching this behavior, took only a second to to realize what he was doing: he was trying with all his might to transport his whole small body into the cozy, loving world of Goodnight Moon (Marcus 1987, p.22) oh-


I'd suppose: trying to prolong the book and the presence of his mother reading. (defer moment when book is closed, she leaves, he is alone w night). & using his feet, bcs yes, in a way trying to keep book open by being physically inside it. ~ but I think he may want the reading, his mother there, as he wants the world of the book.