"This kind of place would make a good theatre for a class in astronomy,"
said I, "or for the meetings of the Interplanetary Congress of
Astronomers, in the year 2000. You can turn on the stars and planets
when you please. I wish you would give me a lecture on the subject now.
My knowledge is a little the worse for wear, and a man ought to know
something of the worlds around him--especially if he intends to visit
them."

"I should only bore you with an old story."

"Not at all. You cannot be too simple and elementary. Regard me as a
small boy in the stage of

"'Twinkle, twinkle, little star,
How I wonder what you are!'"

"Very well, my little man, have you any idea how many stars you can see
on a clear night?"

"Billions."

"No, Tommy. You are wrong, my dear boy. Go to the foot of your class.
With the naked eye we can only distinguish three or four thousand, but
with the telescope we are able to count at least fifty millions. They
are thickest in the Milky Way, which, as you can see, runs all round the
heavens, over your head, and under your feet, like an irregular tract of
hazy light, a girdle of stars in short. Of course we cannot tell how
many more there are beyond the range of vision, or what other galaxies
may be scattered in the depths of space. The stars are suns, larger or
smaller than our own, and of various colours--white, blue, yellow,