Nothing is as easy as it looks. Everything takes longer than you think. Whenever you set out to do something, something else must be done first. Every solution breeds new problems. It is impossible to make anything foolproof because fools are so ingenious.
Nature always sides with the hidden flaw.
When you dial a wrong number, you never get a busy signal. Things get worse under pressure. Smile . . . Everything goes wrong all at once. In nature, nothing is ever right.