Author is not talking about indexing with time, rather they are talking about just writing with time.. viz you write forward as time flows forward.. You should

Author is not talking about indexing with time, rather they are talking about just writing with time.. viz you write forward as time flows forward.. You should definitely index by topic/content. Eg Cats: 1,5,7,8,22,23,55 Dogs: 2,3,9,10 ...