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The Kelpie is the supernatural shape-shifting water horse that haunts the rivers and streams of Scotland. It is probably one of the best known of Scottish water spirits and is often mistakenly thought to haunt lochs, which are the reserve of the Each Uisge.
The creature could take many forms and had an insatiable appetite for humans; its most common guise was that of a beautiful tame horse standing by the riverside - a tempting ride for a weary traveller. Anybody foolish enough to mount the horse - perhaps a stranger unaware of the local traditions - would find themselves in dire peril, as the horse would rear and charge headlong into the deepest part of the water, submerging with a noise like thunder to the travellers watery grave. The Kelpie was also said to warn of impending storms by wailing and howling, which would carry on through the tempest. This association with thunder - the sound its tail makes as it submerges under water - and storms, may be related to ancient worship of river and weather deities by the ancient Celts, although this is difficult to substantiate.
One of the other forms assumed by the Kelpie was that of a hairy humanoid, who would leap out from the riverside vegetation to attack passing travellers. Their grip was said to be like that of a vice, crushing the life out of anybody unfortunate enough to come within the Kelpies clutches.
The Kelpie was thought to inhabit rivers throughout Scotland, and one is recorded as being banished by St Columba from the River Ness, which later became associated with the Loch Ness Monster. Another Kelpie abode was the river Conon (Conan) in Perthshire, which was treacherous in flood, and associated with other dangerous water spirits.
There was one way in which a Kelpie could be defeated and tamed; the Kelpies power of shape shifting was said to reside in its bridle, and anybody who could claim possession of it could force the Kelpie to submit to their will. A Kelpie in subjugation was highly prized, it had the strength of at least 10 horses and the endurance of many more, but the fairy races were always dangerous captives especially those as malignant as the Kelpie. It was said that the MacGregor clan were in possession of a Kelpies bridle, passed down through the generations from when one of their clan managed to save himself from a Kelpie near Loch Slochd.
As I have mentioned above many of these water spirits may be related to ancient worship passed down in the diluted form of folk tales and legends. The wide distribution of the tales and the similarity in nature of water spirits lends weight to this argument. Water must have had a duel nature to our ancestors as a life giver but also a life taker reflected in the treachery of water spirits.