The words of Philosopher-Specialist Harl:
Possession of an ultimate weapon, of an ultimate threat to all of the life that shares this planet, brings with it no guarantee of supremacy. The very act of threatening to use such a weapon, based on certain conditions, puts control of that weapon into the hands of all those who control the conditions. You face the problem of what to do when these others say to you, "So use your weapon!" In this manner, many will have the weapon. Even more to the point, anyone able to threaten the possessor of such a weapon also possesses it. Thus, an ultimate weapon is useless unless those who control it can temper the weapon's violence. The weapon must have degrees of application that are less than ultimate. Take your lesson from the defense mechanisms everywhere visible in the insects who provide us with our pattern for survival. The spikes and prickles, the stingers and thorns, the burning chemicals and poisoned spears that jut angrily into the air, all of these are, first, defense mechanisms. They say, "Don't threaten me."