AN Whitehead, on separating data and control planes:<p>"Operations of thought are like cavalry charges in a battle — they are strictly limited in number, they require fresh horses, and must only be made at decisive moments."<p>To understand this, one must realise that a horse can only go full out (<20 HP) for a minute or two, and even at 80% will be exhausted in under 15 minutes. Infantry may, and does, grind, but cavalry relies on timing[1]. (Why use cavalry then? Because, properly deployed, they turned minor routs into decisive victories. Consider Guagamela.)<p>[1] There is a nice anecdote about von Seydlitz and Frederick the Great. Von Seydlitz is waiting with his cavalry squadrons for opportunity to ripen. Frederick sends a messenger to him to attack. Von Seydlitz responds, "later." A new messenger comes, "you are ordered to attack." Von Seydlitz responds, "in due course." Finally a messenger arrives, "the king says if you do not attack instantly you will be beheaded." Von Seydlitz responds, "please inform his Excellency that my head will be at his disposal <i>after</i> the battle, but <i>during</i> the battle I still need to use it in his service."