We said that a meteor travels one hundred times as swiftly as a rifle-bullet; but even this great speed seems almost nothing when compared with the speed of light, which is ten thousand times as great.  Suppose some brilliant outbreak of light were to take place in a distant star—­an outbreak which would be of such intensity that the flash from it would extend far and wide throughout the universe.  The light would start forth on its voyage with terrific speed.  Any neighboring star which was at a distance of less than one hundred and eighty-five thousand miles would, of course, see the flash within a second after it had been produced.  More distant bodies would receive the intimation after intervals of time proportioned to their distances.  Thus, if a body were one million miles away, the light would reach it in from five to six seconds, while over a distance as great as that which separates the earth from the sun the news would be carried in about eight minutes.  We can calculate how long a time must elapse ere the light shall travel over a distance so great as that between the star and our earth.  You will find that from the nearest of the stars the time required for the journey will be over three years.  Ponder on all that this involves.  That outbreak in the star might be great enough to be visible here, but we could never become aware of it till three years after it had happened.  When we are looking at such a star to-night we do not see it as it is at present, for the light that is at this moment entering our eyes has travelled so far that it has been three years on the way.  Therefore, when we look at the star now we see it as it was three years previously.  In fact, if the star were to go out altogether, we might still continue to see it twinkling for a period of three years longer, because a certain amount of light was on its way to us at the moment of extinction, and so long as that light keeps arriving here, so long shall we see the star showing as brightly as ever.  When, therefore, you look at the thousands of stars in the sky to-night, there is not one that you see as it is now, but as it was years ago.

I have been speaking of the stars that are nearest to us, but there are others much farther off.  It is true we cannot find the distances of these more remote objects with any degree of accuracy, but we can convince ourselves how great that distance is by the following reasoning.  Look at one of the brightest stars.  Try to conceive that the object was carried away further into the depths of space, until it was ten times as far from us as it is at present, it would still remain bright enough to be recognized in quite a small telescope; even if it were taken to one hundred times its original distance it would not have withdrawn from the view of a good telescope; while if it retreated one thousand times as far as it was at first it would still be a recognizable point in our mightiest instruments.  Among the stars which we can see with our telescopes, we feel confident there must be many from which the light has expended hundreds of years, or even thousands of years, on the journey.  When, therefore, we look at such objects, we see them, not as they are now, but as they were ages ago; in fact, a star might have ceased to exist for thousands of years, and still be seen by us every night as a twinkling point in our great telescopes.