The Astronomer Francesco Sizi offered the following argument to show why, contrary to what his contemporary, Galileo, claimed to have seen through his telescope, there could be no satellites circling around Jupiter:
There are seven windows in the head, two nostrils, two ears, two
eyes and a mouth; so in the heavens there are two favorable
stars, two unpropitious, two luminaries, and Mercury alone
undecided and indifferent. From which and many other similar
phenomena of nature such as the seven metals, etc., which it were
tedious to enumerate, we gather that the number of planets is
necessarily seven...Moreover, the satellites are invisible to the
naked eye and therefore can have no influence on the earth and
therefore would be useless and therefore do not exist.