"Equo ne credite," warned Laocoon, the incumbent Trojan priest when the town was under siege by Ulysses and all those other Greeks. "Do not believe the horse" - and, of course, as we know, he went on to deliver that celebrated warning which, if heeded, might well have changed the story-line of both the Aeneid and the Iliad. "Timeo Danaos et dona ferentes," he declared: "I fear the Greeks when they come bearing gifts."
But does equo ne credite make sense in weather matters? Certainly our ancestors were not of that opinion, and placed considerable faith in horses as predictors of the rain. There were a variety of symptoms: if horses stretched out their necks and sniffed the air, it was a sign of rain; so it was, too, if they were restless or uneasy, or if they assembled in the corner of a field with their tails facing in the direction of the wind.
Sir Walter Scott in Quentin Durward has yet another version of this horsy lore. He tells how Louis XI of France was soaked with rain after he refused to believe the prophecy of a wayside charcoalburner. But when the forecaster was asked afterwards about his methods, he gave the credit to his horse; on the approach of rain the animal invariably pricked its ears forward, walked more slowly than usual, and tried to rub its back against any wall it passed.
Horses react to the weather in many other ways. They are particularly sensitive, it seems, to lightning and to thunder, even to the extent of causing themselves serious injury by bolting in a thunderstorm, so when unexplained injuries occur to thoroughbreds, climatological records often reveal a thunderstorm as being the likely cause. And it was always so; Horace, if I read his text correctly after all these years, seemed to attribute similar equine behaviour to Jupiter, the Roman god of thunder:
. . . namque Diespiter
Igni corusco nubila dividens
Egit equos.
"Jupiter, indeed, dividing up the clouds with shimmering fire, spurred on the horses."
As it happens, the horse has even left its mark upon the general circulation of our planet. A semi-permanent feature of the weather map is an area of high pressure, known nowadays, for the obvious reasons, as the Azores High. In the days of the old sailing ships, however, this zone of very light winds was a frequent cause of inconvenience to ancient mariners. The region became known as the "Horse Latitudes", allegedly because any horses aboard were thrown overboard to conserve the water they would otherwise consume in a ship becalmed for an extended period.