It is not the transactions of to-day that we read in the heavens, but it is history, some of it older than the time of Adam.  Those stars may have been smitten out of existence decades of centuries ago, but their poured-out light is yet flooding the heavens.

It goes both ways at once in the same place, without interference.  We see the light reflected from the new moon to the earth; reflected back from the house-tops, fields, and waters of earth, to the moon again, and from the moon to us once more—­three times in opposite directions, in the same place, without interference, and thus we see “the old moon in the arms of the new.”

Constitution of Light.

[Illustration:  Fig. 6.—­White Light resolved into Colors.]

Light was once supposed to be corpuscular, or consisting of transmitted particles.  It is now known to be the result of undulations in ether.  Reference has been made to the minuteness of these undulations.  Their velocity is equally wonderful.  Put a prism of glass into a ray of light coming into a dark room, and it is [Page 25] instantly turned out of its course, some parts more and some less, according to the number of vibrations, and appears as the seven colors on different parts of the screen.  Fig. 6 shows the arrangement of colors, and the number of millions of millions of vibrations per second of each.  But the different divisions we call colors are not colors in themselves at all, but simply a different number of vibrations.  Color is all in the eye.  Violet has in different places from 716 to 765,000,000,000,000 of vibrations per second; red has, in different places, from 396 to 470,000,000,000,000 vibrations per second.  None of these in any sense are color, but affect the eye differently, and we call these different effects color.  They are simply various velocities of vibration.  An object, like one kind of stripe in our flag, which absorbs all kinds of vibrations except those between 396 and 470,000,000,000,000, and reflects those, appears red to us.  The field for the stars absorbs and destroys all but those vibrations numbering about 653,000,000,000,000 of [Page 25] vibrations per second.  A color is a constant creation.  Light makes momentary color in the flag.  Drake might have written, in the continuous present as well as in the past,

 “Freedom mingles with its gorgeous dyes
  The milky baldrick of the skies,
  And stripes its pore celestial white
  With streakings of the morning light.”

Every little pansy, tender as fancy, pearled with evanescent dew, fresh as a new creation of sunbeams, has power to suppress in one part of its petals all vibrations we call red, in another those we call yellow, and purple, and reflect each of these in other parts of the same tender petal.  “Pansies are for thoughts,” even more thoughts than poor Ophelia knew.  An evening cloud that is dense enough to absorb all the faster and weaker vibrations, leaving only the stronger to come through, will be said to be red; because the vibrations that produce the impression we have so named are the only ones that have vigor enough to get through.  It is like an army charging upon a fortress.  Under the deadly fire and fearful obstructions six-sevenths go down, but one-seventh comes through with the glory of victory upon its face.