I've found that when you leave me too much time to think, I create all sorts of impossible/improbable/....
Let me put you in the situation I've envisioned myself a paranoid, potential victim of. You are told by some very important person (let us go with a tyrannical boss-like figure) that you must absolutely, positively not forget some very important meeting with some other very important person (possibly the oppressive boss-like figure to your own tyrannical boss-like figure) on some very distant (but equally very important) date in the future.
The question remains: where would you record this not-to-be-forgotten meeting time? How would you ensure that you could in no way whatsoever miss this important event? Where is information perfectly secure?
A planner? I've lost many a good-intentioned daily calendar.
A phone? Gravity over toilet bowls seems to work better than anywhere else.
A dry erase board? The name itself kills that idea.
A friend? I've already forgot the instances I've even been asked to remember something, not to mention the actual messages involved.
Memory? Tell that to last night's oven-mutilated dinner.
I find it remarkable that the only place I could trust myself to place such invaluable information would be to send myself an e-mail...