hey goiitians m new to dis forum..well i always used to cum to dis forum but dis is my first post n im answering dis one coz dis is the only ques which i think i'll be able to ans..hehe..well i remember i had a long discussion with my teacher on this topic..well my point of view is tat the satement means tat wtever we think is illogical at this present moment might turn out to be the truth some time later..like for example rite now time travel seems so illogical but maybe after few yrs it will becum a reality..if u take ex frm the chapter the guy in tat chapter believs tat 3rd level exsisted through which he could enter into a diff world but nobody believes him but later on it turns out to be true ...though the exsistence of such a level  which can take u back into time is scientifically impossible but then too it xsisted .. the things which do not have a scientic explaination dosen't mean tat they don't exsist at all..so we cannot disacrd nething as impossible...coz nething tat seems impossible rite now  may  be scientifically proven after some time..like the xsistence of god..