The Roman statesman Gaius Plinius Secundus, popularly known as Pliny, was a little like Jim Dooge. Prof Dooge, our quondam Foreign Minister, has combined a busy life of public affairs with prodigious and widely-acclaimed activity in the realm of science. So, too, did Pliny.
The latter's Natural History, a vast encyclopaedia of general and scientific knowledge, was the authoritative source for nearly everything for many centuries. It contained, for example, an explanation for the rainbow.
"The common occurrences that we call rainbows," Pliny says, "are not miraculous or clues to future happenings, for they do not even reliably portend a shower of rain or sunny weather. Their obvious explanation is that a ray of sunshine, striking a hollow cloud, has had its point repelled and reflected back in the direction of the sun, and their diverse colouring is due to the ambient mixture comprising fires, clouds and air."
Of course, we know that that is not entirely true. Nowadays we recognise the rainbow as an optical phenomenon caused by the reflection of bright sunlight from a distant curtain of gently falling raindrops, the different hues resulting from the splitting of the white sunlight into its constituent colours of the spectrum. But Pliny's notions were nearer the mark than those of many a savant around that time.
In Norse mythology, for example, the rainbow was simply a means of entering heaven. Valhalla was the home of Odin who, seated on his throne, surveyed all Heaven and Earth and feasted with his chosen heroes. The only entrance to this Nordic paradise was by the "bridge of the gods" - the rainbow - that connected it to Earth.
In other cultures the rainbow, as its name suggested, was a bow used by the thunder god to shoot arrows of lightning to the ground. Alternatively, as it was in Celtic legend, the rainbow could be an enormous snake with flaming eyes; some believed that this serpent drank from pools of water where its ends touched the Earth, and that it could inhabit these pools, ready to devour those unfortunate enough to be caught bathing there when the monster came along.
But the rainbow could be good news, too. Untold treasures, some said, lay at the end of every rainbow, the exact form it took - whether silver, gold, or even pearls - depending on the local folklore. One might have to dig a hole to find it at the point where the rainbow met the ground, or it might be sufficient to place a basket under one of the pillars on which the rainbow was reputedly supported.