The lightning reaches our perception sooner than the thunder, though it actually occurs after it, since it is the nature of that which is heard to travel less quickly than that which is seen; for the latter is visible at a distance, while the former is only heard when it reaches the ear, especially since the one, the fiery element, travels faster than anything else, while the other, being of the nature of air, is less swift and only reaches the ear by actually striking upon it.