“It appears that here and there some of our modern ideas were anticipated by writers of the Middle Ages. Thus, Nicole Oresme... first conceived the notion of fractional powers, afterwards, rediscovered by Stevin, and suggested a notation [other than our modern notation]. Since 4^3 = 64 and 64^\frac{1}{2} = 8, Oresme concluded that 4^\frac{3}{2} = 8. Some of the mathematicians of the Middle Ages possessed some idea of a function. Oresme even attempted a graphic representation. But of a numeric dependence of one quantity upon another, as found in Descartes, there is no trace among them.”