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The following is the opinion of our Stoic sage Zeno. He is convinced that the stars act in concert, and unite their rays with one another—a partnership in light which creates the image of a more elongated star. Therefore some persons suppose that comets have no real existence, and that it is only the appearance of them that is reproduced through the reflection of neighbouring stars or the union of stars that stick together. Some, again, say that comets are true stars, but with orbits of their own, and that after certain periods they come out into the view of mankind. Some allow their existence but refuse them the title of stars, because they glide out of sight without long duration, and within a brief space are scattered to the winds.