I find then, said I, it is useless to attempt raising your compassion for the comets: I hope, however, you will not refuse it to the inhabitants of a vortex whose sun has been extinguished, and who are thus condemned to perpetual darkness. Suns extinguished? cried she. Yes, undoubtedly, I replied. The ancients saw certain fixed stars which are no longer visible.[54] These suns have been deprived of their light: ruin must have ensued throughout the vortex; a general mortality on all the planets; for how could existence be maintained without the sun? The thought is too dreadful, said she; is it not possible to evade it? I'll tell you, answered I, what some very intelligent people have imagined. They think that the fixed stars that have disappeared are not extinct, but partly darkened; that is to say, that they have one side obscure; the other luminous: that as they turn on themselves, they first present the light part to us, and then the dark, when that is the case we cease to see them. Apparently the fifth moon belonging to Saturn is in this condition, for during one part of its revolution we entirely lose sight of it; at which time it is not most remote from the earth; on the contrary, it is then sometimes nearer than when visible. Though this moon is a planet, and therefore cannot exactly guide our opinion with respect to suns, yet we may suppose that a sun can be partly covered by fixed spots. To spare you the pain of believing the other opinion, we will adopt this, which is more agreeable: but I can only receive it when applied to such fixed stars as have a regular time for appearing and disappearing, as some have lately been observed to do, otherwise we cannot suppose them half suns. What must we say to the stars that disappear, and do not become visible after a time that would certainly have been sufficient for turning on their axis? You are too just to require me to believe that they are half suns: however I will do all in my power to serve you; we will conclude that these stars are not extinguished, but plunged in the unfathomable depth of the sky, and thus become invisible; in this case the vortex would accompany its sun, and all go on as usual. It is true that the greatest part of the fixed stars have not any motion which removes them farther from us, for if they were not always equally distant, they would sometimes appear larger, sometimes smaller; but that is not the case. [Footnote 54: In 1572 and 1604, some beautiful stars appeared to burst into light, and afterwards become extinct. Astron. Art. 792.]