by science, the sky is known to be merely an optical
appearance due to the partial absorption of the solar rays in
passing through a thick stratum of atmospheric air; the clouds
are known to be large masses of watery vapour, which descend
in rain-drops when sufficiently condensed; and the lightning
is known to be a flash of light accompanying an electric
discharge. But these conceptions are extremely recondite, and
have been attained only through centuries of philosophizing
and after careful observation and laborious experiment. To the
untaught mind of a child or of an uncivilized man, it seems
far more natural and plausible to regard the sky as a solid
dome of blue crystal, the clouds as snowy mountains, or
perhaps even as giants or angels, the lightning as a flashing
dart or a fiery serpent. In point of fact, we find that the
conceptions actually entertained are often far more grotesque
than these. I can recollect once framing the hypothesis that
the flaming clouds of sunset were transient apparitions,
vouchsafed us by way of warning, of that burning Calvinistic
hell with which my childish imagination had been unwisely
terrified;[33] and I have known of a four-year-old boy who
thought that the snowy clouds of noonday were the white robes
of the angels hung out to dry in the sun.[34] My little
daughter is anxious to know whether it is necessary to take a
balloon in order to get to the place where God lives, or
whether the same end can be accomplished by going to the
horizon and crawling up the sky;[35] the Mohammedan of old was
working at the same problem when he called the rainbow the
bridge Es-Sirat, over which souls must pass on their way to
heaven. According to the ancient Jew, the sky was a solid
plate, hammered out by the gods, and spread over the earth in