visit the moon, or cross it, or are held in temporary suspension near it—then some of them must often have been within the diameter of an astronomer's hypnosis.
Our general expression:
That, upon the oceans of this earth, there are regularized vessels, but also that there are tramp vessels:
That, upon the super-ocean, there are regularized planets, but also that there are tramp worlds:
That astronomers are like mercantile purists who would deny commercial vagabondage.
Our acceptance is that vast celestial vagabonds have been excluded by astronomers, primarily because their irresponsibilities are an affront to the pure and the precise, or to attempted positivism; and secondarily because they have not been seen so very often. The planets steadily reflect the light of the sun: upon this uniformity a system that we call Primary Astronomy has been built up; but now the subject-matter of Advanced Astronomy is data of celestial phenomena that are sometimes light and sometimes dark, varying like some of the satellites of Jupiter, but with a wider range. However, light or dark, they have been seen and reported so often that the only important reason for their exclusion is—that they don't fit in.
With dark bodies that are probably external to our own solar system, I have, in the provincialism that no one can escape, not much concern. Dark bodies afloat in outer space would have been damned a few years ago, but now they're sanctioned by Prof. Barnard—and, if he says they're all right, you may think of them without the fear of doing something wrong or ridiculous—the close kinship we note so often between the evil and the absurd—I suppose by the ridiculous I mean the froth of evil. The dark companion of Algol, for instance. Though that's a clear case of celestial miscegenation, the purists, or positivists, admit that's so. In the Proceedings of the National Academy of Science, 1915-394, Prof. Barnard writes of an object—he calls it an "object"—in Cephus. His idea is that there are dark, opaque bodies outside this solar system. But in the Astrophysical Journal, 1916-1, he modifies into regarding them as "dark nebulæ." That's not so interesting.
We accept that Venus, for instance, has often been visited by other worlds, or by super-constructions, from which come cinders and coke and coal; that sometimes these things have reflected light and have been seen from this earth—by professional astronomers.
