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twixt natural history and metaphysics ; so the former part ap- 

 proaches nearer to natural history, and the latter to metaphysics. 

 Concrete physics has the same division with natural history ; 

 being conversant either about celestial appearances, meteors, 

 and the terrestrial globe ; or about the larger assemblages of 

 matter, called the elements ; and the lesser or particular bodies ; 

 as also about praetergenerations and mechanics. For in all 

 these, natural history examines and relates the matters of fact ; 

 and physics their instable, or material and efficient causes. And 

 among these parts of physics, that is absolutely lame and in- 

 complete, which regards the celestial bodies, though for the 

 dignity of the subject it claims the highest regard. Astronomy, 

 indeed, is well founded in phenomena; yet it is low and far 

 from solid. But astrology is in many things destitute of all 

 foundation. And to say the truth, astronomy itself seems to 

 offer Prometheus's sacrifice to the understanding; for as he 

 would have imposed upon Jupiter a fair large hide, stuffed with 

 straw, and leaves, and twigs, instead of the ox itself, so 

 astronomy gives us the number, situation, motion, and periods 

 of the stars, as a beautiful outside of the heavens, whilst the 

 flesh and the entrails are wanting ; that is, a well-fabricated sys- 

 tem, or the physical reasons and foundations for a just theory, 

 that should not only solve phenomena, as almost any ingenious 

 theory may do, but show the substance, motions, and influences 

 of the heavenly bodies, as they really are. For those dogmas 

 are long since exploded, which asserted the rapture of the first 

 morn and the solidity of the heavens, in which the stars were 

 supposed fastened like nails in the vaulted roof of a hall, and 

 other opinions almost as silly ; viz., that the zodiac has several 

 poles; that there exists a movement of resilience against the 

 rapture of the first motion ; that all parts of the firmament are 

 wheeled round in perfect circles, with eccentric and epicycles 

 to preserve their circular rotation ; that the moon has no influ- 

 ence over bodies higher in the heavens ; the absurdity of which 

 notions have thrown men upon the extravagant idea of the 

 diurnal motion of the earth, an opinion which we can demon- 

 strate to be most false.? But scarce any one has inquired into 

 the physical causes of the substance of the heavens, stellar and 

 interstellar ; the different velocities of the celestial bodies with 

 regard to one another ; the different accelerations of motion in 

 the same planet; the sequences of their motion from east to 



