The human race, according to Dr Johnson, has a tendency to "represent as perpetual that which is only frequent, or as constant that which is really casual". This unscientific trait must be held accountable for the meteorological beliefs surrounding St Swithin's Day, which falls tomorrow, July 15th.
St Swithin was a near-contemporary of King Alfred the Great in the 9th century. Alfred was king of the Saxon kingdom of Wessex, an area dominated by the city of Winchester, and he earned his sobriquet by his repeated success at warding off the Danes. Swithin's fame, on the other hand, is meteorological.
Swithin was the Bishop of Winchester, and reputedly a good and humble one. Indeed, he was so good and humble that when he died in 862 he left instructions that he was to be buried outside his cathedral "in a vile and unworthy place", where water from the eaves might fall upon his grave.
There Swithin lay for more than 100 years. In due course, however, word came that the former bishop was to be promoted saint, and the monks came to think of it as inappropriate that the remains of such a holy man should rest in such a lowly place. They prepared to move Swithin with solemn ceremony inside the cathedral, and the appointed day was July 15th, 1971.
According to legend, a tempest raged on that fateful day, and the removal was postponed. The next day it rained again and for 40 days and 40 nights it rained without intermission.
Eventually, realising the folly of trying to thwart the saintly whim, the monks erected a simple chapel over the grave, and left the humble bishop where he was.
But even to this day, Swithin cannot resist dabbling with the elements around this time of year. It is said that if it rains on his feast day, July 15th, then rain will occur on each of the following 40 days.
So should we bother with the legend of St Swithin's Day? Some meteorologists are of the view that by around mid-July each year, most Irish summers have settled down to a pattern which often persists for the remainder of the season, either cool, rather wet and changeable, or else mostly warm and sunny.
If this be so, the general character of the weather around St Swithin's Day may well not be too bad a guide as what to expect for the remainder of the summer.
Others, however, are more inclined to agree with the poet John Gay: Let not such vulgar tales debase thy mind, For neither Paul nor Swithin Rules the clouds and wind.