Note 26 — Chapter III · DETAILED CONSIDERATION OF VARIOUS CONCEPTS OF PHYSICS (continued 2)
Reading edition
No difficulty arises from the asymmetric character of light in assigning an infinite velocity to light because those physical operations by which we discover which is the source and which the sink are entirely distinct from the operations by which a velocity is measured; or in other words, even in the limit, it still has meaning to say that an infinite velocity has a direction associated with it.