I was pleased to learn more about the US Postal Service Motto's origin...and to think I actually read Herodotus in college and missed this entirely. The image of horse and man is especially sweet...

	It is said that as many days as there are in the whole journey, so many are the men and horses that stand along the road, each horse and man at the interval of a day’s journey; and these are stayed neither by snow nor rain nor heat nor darkness from accomplishing their appointed course with all speed.
	HERODOTUS, Herodotus, trans. A.D. Godley, vol. 4, book 8, verse 98, pp. 96–97 (1924).