Capella to the Earth, traversed space without interruption seventy-one years, eight months, and twenty-four days before it was visible on the Earth. In like manner, the ray of light which leaves the Earth can only arrive at Capella in the same period of time. [Sidenote: Time occupied in the transmission of light.] QUÆRENS. If the luminous ray which comes from that star takes nearly seventy-two years to reach us, it follows that we see the star as it was nearly seventy-two years ago? LUMEN. You are quite right, and this is the fact that I want you take note of specially. [Sidenote: A belated courier.] QUÆRENS. In other words, the ray of light is like a courier who brings despatches from a distant country, and having been nearly seventy-two years on the way, his news is of events that occurred at the time of his departure seventy-two years ago. LUMEN. You have divined the mystery. Your illustration shows me that you have lifted the veil which shrouded it. In order to be still more exact, the light represents a courier who brings, not written news, but photographs, or, strictly speaking, _the real aspect_ of the country from whence he came. We see this living picture such as it appeared, in all its aspects, at the moment when the luminous rays shot forth from the distant orb. Nothing is more simple, nothing more indubitable. When we examine the surface of a star with a telescope we see, not the actual surface as it was at the time of our observation, but such as it was when the light was emitted from that surface. QUÆRENS. This being so, if a star, the light of which takes ten years to reach us, were to be annihilated to-day, we should continue to see it for ten years, since its last ray would not reach us before ten years had elapsed. [Sidenote: We see the past, not the present, aspect of the stars.]