There are only three kinds of mistakes in politics. The first is a simple mistake that can be corrected or undone with relative ease. Such mistakes cause no serious harm to the nation. They only serve to confirm how foolish or inadvertent politicians can be.
The second kind is a serious mistake that can't be corrected or undone easily. Serious mistakes often do harm to the nation and, therefore, should be carefully dealt with. Fortunately, however, in most cases wise politicians will strive to not repeat such mistakes and life goes on.
The third and the worst kind is a fatal mistake that is not only irreversible but also extremely detrimental to the nation. Unfortunately, fatal mistakes are often made out of intuition, coincidence or misjudgment, and politicians do not always recognize when they make them.