fficulty in obtaining permission for learned men to read any
prohibited books, and that he (Kepler) need fear nothing so long as he
remained quiet.

In his various works on Comets, he adhered to the opinion that they
travelled in straight lines with varying velocity. He suggested that
comets come from the remotest parts of ether, as whales and monsters
from the depth of the sea, and that perhaps they are something of the
nature of silkworms, and are wasted and consumed in spinning their own
tails. Napier's invention of logarithms at once attracted Kepler's
attention. He must have regretted that the discovery was not made early
enough to save him a vast amount of labour in computations, but he
managed to find time to compute some logarithm tables for himself,
though he does not seem to have understood quite what Napier had done,
and though with his usual honesty he gave full credit to the Scottish
baron for his invention.

Though Eugenists may find a difficulty in reconciling Napier's
brilliancy with the extreme youth of his parents, they may at any rate
attribute Kepler's occasional fits of bad temper to heredity. His
cantankerous mother, Catherine Kepler, had for some years been carrying
on an action for slander against a woman who had accused her of
administering a poisonous potion. Dame Kepler employed a young advocate
who for reasons of his own "nursed" the case so long that after five
years had elapsed without any conclusion being reached another judge was
appointed, who had himself suffered from the caustic tongue of the
prosecutrix, and so was already prejudiced against her. The defendant,
knowing this, turned the tables on her opponent by bringing an
accusation of witchcraft against her, and Catherine Kepler was
imprisoned and condemned to the torture in July, 1620. Kepler, hearing
of the sentence, hurried back from Linz, and succeeded in stopping the
completion of the sentence, securing his mother's release the following
year, as it was made clear that the only support for the case against
her was her own intemperate language. Kepler returned to Linz, and his
mother at once brought another action for costs and damages against her
late opponent, but died before the case could be tried.

A few months before this Sir Henry Wotton, English Ambassador to Venice,
visited Kepler, and finding him as usual, almost penniless, urged him to
go to England, promising him a warm welcome there. Kepler, however,
would not at