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COGITATIONES

DE

NATURA RERUM.

PRETACE

TO THE

COGITATIONES DE NATURA RERUM.

This piece was printed by Gruter among the Impetus Philosophici ; from which we may probably conclude that it had not been transcribed into the volume of Scripta in Naturali et Universali Philosophiâ': but that is all. There is nothing to determine the date of composition, unless it be the absence of any allusion to the new star in Ophiuchus in the place where the new star in Cassiopeia is mentioned. See note, ş x. The value of the argument will be more easily understocd by comparing the passage in question with a passage of the same import in a work, obviously later, where both these stars are mentioned together. In both cases the question under discussion is the immutability of the heavens. In the Cogitationes de Naturâ Rerum, of which the date is unknown, we find, “... mutationes in regionibus cælestibus fieri, ex cometis quibusdam satis liquet; iis dico qui certam et constantem configurationem cum stellis fixis servarunt; qualis fuit ille qui in Cassiopeâ nostrâ ætate apparuit.” This star in Cassiopeia appeared in 1572. But another of the same kind, and no less remarkable, appeared in September 1604. It is said to have been brighter, when first seen, than Jupiter?; and though its brightness diminished afterwards, it was distinctly visible for more than a year. It attracted so much attention as to be made the subject of three lectures of a popular character, given by Galileo to crowded audiences; and it is difficult to believe either that Bacon did not know of it (he being then 44 years old, and busy at the time with the Advancement of Learning, and quite understanding the significance of the phenomenon ;) or that, if he did, he could have forgotten to mention it when speaking of the other. Accordingly, in the Descriptio Globi Intellectualis, which we know to have been written about the year 1612, the passage which I have just quoted appears in a new form. “Id enim [sc. admirandas in cælo accidere mutationes atque insolentias] perspicitur in cometis sublimioribus, iis nimirum qui et figuram stellæ induerunt absque comâ, neque solum ex doctrinâ parallaxium supra lunam collocati esse probantur, sed configurationem etiam certam et constantem cum stellis fixis habuerunt, et stationes suas servarunt, neque errones fuerunt; quales ætas nostra non semel vidit; primo in Cassiopeâ, iterum non ita pridem in Ophiucho.

i See above, p. 8. 9 Maestlin, quoted in the Life of Gallleo, Library of Ureful Knowledge, p. 16.

That when Bacon wrote the tenth Cogitatio he had not heard of the appearance of this second new star, may be assumed with considerable confidence. The only question is whether such a phenomenon could have been long known to the astronomers of his time, without his hearing of it; of which I can only say that it seems unlikely, and that, in the absence of all evidence to the contrary, the presumption must be that these Cogitationes were composed before 1605. That they were composed before the appearance of the new star in Cygnus, cannot be so safely inferred. That star was much less conspicuous; and it is a fact that Galileo himself, treating this very same argument, mentions both the others without making any allusion to it. See Dial. dei Massimi Sistemi, p. 59. ed. Flor. 1842.

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COGITATIONES DE NATURA RERUM.

COGITATIO I. De sectione corporum, continuo, et vacuo. DOCTRINA Democriti de atomis aut vera est, aut ad demonstrationem utiliter adhibetur. Non facile enim est naturæ subtilitatem genuinam, et qualis in rebus ipsis invenitur, aut cogitatione complecti aut verbis exprimere, nisi supponatur atomus. Accipitur autem duobus sensibus atomus, non multum inter se diversis. Aut enim accipitur pro corporum sectionis sive fractionis termino ultimo sive portione minima; aut pro corpore quod vacuo caret. Quod ad primum attinet, hæc duo posita tuto et certo statui possunt. Alterum, inveniri in rebus dispertitionem et comminutionem, longe ea quæ sub adspectum cadit subtiliorem. Alterum, eam tamen infinitam non esse, nec perpetuo divisibilem. Si quis enim diligenter attendat, reperiet rerum minutias in corporibus continuatis, eas quæ in corporibus fractis et discontinuatis inveniuntur subtilitate longe vincere. Videmus enim parum croci in aqua infusum et agitatum, puta dolium aquæ ita inficere, ut ab alia aqua pura etiam visu distingui possit. Quæ certe dispertitio croci per aquam, subtilitatem exquisitissimi pulveris superat. Quod manifestum fiet, si tantundem pulveris ligni Brasilii, vel balaustiorum, vel alicujus rei optime coloratæ (quæ tamen croci lentorem ad se in liquoribus aperiendum et incorporandum non habeat) immisceas. Itaque ridiculum erat, atomos pro parvis illis corpusculis quæ sub radiis solis conspiciuntur accipere. Ea enim pulveris instar sunt; atomum autem, ut ipse Democritus aiebat, nemo unquam vidit, aut videre possit. Sed ista rerum dispertitio in odoribus multo magis mirabilem se ostendit. Etenim si parum croci dolium aquæ colore, at parum zibethi cænaculum amplum odore, imbuere et inficere potest, et subinde

I Nam in Gruter's copy. - J. S.

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