The “felt” element in troops, not expressible in figures, had to be guessed at by the equivalent of Plato’s δοξα , and the greatest commander of men was he whose intuitions most nearly happened. Nine-tenths of tactics were certain enough to be teachable in schools; but the irrational tenth was like the kingfisher flashing across the pool, and in it lay the test of generals. It could be ensued only by instinct (sharpened by thought practising the stroke) until at the crisis it came naturally, a reflex. There had been men whose δοξα so nearly approached perfection that by its road they reached the certainty of επιστημη . The Greeks might have called such genius for command νοησις had they bothered to rationalise revolt.