_Theophilus._ But, if we are to accept the results of the labours of recent naturalists, man exists on the earth only within 100,000 years, and some of those stars may have been extinct during all that time, so that the human race may have been contemplating stars no longer in being for 100,000 years. To what strange consequences does such a science lead us! _The Author._ Yes, the luminous rays which these stars send us from the deepest depths of space may perhaps be emanations from solar systems no longer in existence. The present shows us only the past. There may be stars so profoundly lost in immensity, that their light has not yet had time to reach us. They exist, but we cannot see them, not because the telescope could not discover them, but because thousands of centuries are required for the journey of their luminous rays to our earth, and those thousands of centuries have not yet elapsed; so that this grand spectacle is reserved, in that awfully remote future, for our descendants. And now, my friend, will you not acknowledge with me, that the universe, considered merely by the distances which separate us from the stars, and the stars from each other, is truly the Infinite? _Theophilus._ Yes, it is the Infinite which unfolds itself before my eyes. Let me breathe a moment. _The Author._ If we contemplate the number of the stars, we shall also have the perspective of the Infinite. It is easy to reckon those of the first magnitude, _i.e._, the nearest to us. They are 20. Those of the second magnitude are 65; of the third, 170. The number of the stars increases as their visibility diminishes, in a very rapid proportion. The number of stars of each class of visibility, in apparent magnitude, is three times greater than that of the stars of the preceding class. There are 500 stars of the fourth, 1500 of the fifth, 4500 of the sixth magnitudes. The stars visible by the naked eye are 6000 in number. A practised eye can succeed in counting the 6000 stars in the two hemispheres. [Illustration: Fig. 6.--A Corner of the Constellation of Gemini.]