You could bring this argument to science where new developments (cloning and GM foods being the most publicised examples) have served to further divide and perplex the Western world rather than bring about the positive effects that the scientists had hoped for. Admittedly, the reactionary media has played a considerable part in this but the principle remains.
Knowledge of the past has a similar effect. It is statistically incorrect to predict lottery balls on past precedent. Exactly the same number of balls are released in each draw and all are identical in shape, size and weight so all have exactly the same chance of turning up as each other. If number 39 has appeared every time for the last 9 weeks, it still has no more chance than the others of appearing this week.
This principle can apply to our emotional lives too. Just because you had more bad days than good last year (and maybe for several years before that), it doesn’t mean that the pattern will repeat this year. The past is a purely cerebral concept (as is all time, it is human instinct to make patterns in order to make sense of the world after all) and not in diaries, history books or other people’s words which are really only relics at best. Whilst you may not be able to rid yourself of these physical relics, you can most importantly rid yourself of the mental ones because the memory is a volatile and selective thing and you should never base your unhappiness on it.
So knowledge isn’t all it’s cracked up to be. However, what’s to say that the knowledge I’ve attempted to impart to you is any better?