wipikedia

With all the time you spend watching TV," he tells me, "you could have written a novel by now." It's hard to disagree with the sentiment -- writing a novel is undoubtedly a better use of time than watching TV -- but what about the hidden assumption? Such comments imply that time is "fungible" -- that time spent watching TV can just as easily be spent writing a novel. And sadly, that's just not the case.

Time has various levels of quality.