s slender income, and was reduced to
keeping a tavern. Young John Kepler was thereupon taken from school,
and employed as pot-boy between the ages of nine and twelve. He was a
sickly lad, subject to violent illnesses from the cradle, so that his
life was frequently despaired of. Ultimately he was sent to a monastic
school and thence to the University of Tuebingen, where he graduated
second on the list. Meanwhile home affairs had gone to rack and ruin.
His father abandoned the home, and later died abroad. The mother
quarrelled with all her relations, including her son John; who was
therefore glad to get away as soon as possible.

All his connection with astronomy up to this time had been the hearing
the Copernican theory expounded in University lectures, and defending it
in a college debating society.

An astronomical lectureship at Graz happening to offer itself, he was
urged to take it, and agreed to do so, though stipulating that it should
not debar him from some more brilliant profession when there was a
chance.

For astronomy in those days seems to have ranked as a minor science,
like mineralogy or meteorology now. It had little of the special dignity
with which the labours of Kepler himself were destined so greatly to aid
in endowing it.

Well, he speedily became a thorough Copernican, and as he had a most
singularly restless and inquisitive mind, full of appreciation of
everything relating to number and magnitude--was a born speculator and
thinker just as Mozart was a born musician, or Bidder a born
calculator--he was agitated by questions such as these: Why are there
exactly six planets? Is there any connection between their orbital
distances, or between their orbits and the times of describing them?
These things tormented him, and he thought about them day and night. It
is characteristic of the spirit of the times--this questioning why there
should be six planets. Nowadays, we should simply record the fact and
look out for a seventh. Then, some occult property of the number six was
groped for, such as that it was equal to 1 + 2 + 3 and likewise equal to
1 x 2 x 3, and so on. Many fine reasons had been given for the seven
planets of the Ptolemaic system (see, for instance, p. 106), but for
the six planets of the Copernican system the reasons were not so cogent.

Again, with respect to their successive distances from the sun, some law
would seem to regulate their distance, but it was not known.
(Parenthetica