I'm looking for a source (of which I've only ever read a quote) discussing the then seven known planets. In particular, I'm looking for the part where the author explains why that number seven makes sense with reference to (I think a Christian) God. His explanation goes something like this: the planets are holes in a celestial sphere; God mirrors those in the sphere of our own heads; and so just as there are seven holes in the head -- one mouth, plus two each of nostrils, eyes, and ears -- so are there seven planets in the heavens.

I think the writer was one of the Bacons, and probably Roger, in which case a likely candidate is his Opus Majus. But so far I haven't been able to find what I'm after.


This probably refers to the "argument" of the Florentine astronomer Francesco Sizzi against the validity of Galileo's discovery of the moons of Jupiter. His "argument" was apparently quoted from the introduction to Francis Bacon, A Selection of His Works (where it illustrates the context of the times), and thereby entered the internet, but it is (thankfully) not Bacon's. Here is the full quote as translated in Fahie, Galileo, his life and work, p.103:

"There are seven windows given to animals in the domicile of the head, through which the air is admitted to the tabernacle of the body, to enlighten, to warm, and to nourish it. What are these parts of the microcosmos? Two nostrils, two eyes, two ears, and a mouth. So in the heavens, as in a macrocosmos, there are two favourable stars, two unpropitious, two luminaries, and Mercury undecided and indifferent.

From this and many other similarities in nature, such as the seven metals, etc., which it were tedious to enumerate, we gather that the number of planets is necessarily seven. Moreover, these satellites of Jupiter are invisible to the naked eye, and therefore can exercise no influence on the earth, and therefore would be useless, and therefore do not exist. Besides, the Jews and other ancient nations, as well as modern Europeans, have adopted the division of the week into seven days, and have named them after the seven planets. Now, if we increase the number of the planets, this whole and beautiful system falls to the ground."

The "logic" is ironclad.

  • 1
    $\begingroup$ Superb! That’s the very thing I was looking for. Thanks a bunch. $\endgroup$
    – tkp
    Sep 3 '21 at 22:58
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    $\begingroup$ FWIW, I read it not on the Internet, but in a book that was probably pre Internet (or at least pre Eternal September). The particular point being made was how very smart people, who say very smart things, can still also come up with complete guff. Nonetheless, based on what you’ve said, the author I read may have missed the fact that in this case the guff did not actually come from Bacon himself, thereby weakening his (the author’s) point somewhat (albeit not irredeemably). $\endgroup$
    – tkp
    Sep 3 '21 at 23:04
  • $\begingroup$ The bit comparing the number of planets to the number of openings in the face feels like relatively normal-for-the-time argument to divine order and all that, but then the latter half of the quote feels more like what you'd get out of some drunken academic at a bar who's really angry that their rival made a discovery before them. Something about it is just really amusing to me. $\endgroup$
    – Hearth
    Sep 4 '21 at 20:46

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