Allegorical stories of saints battling with giants, monsters and demons may be interpreted as symbolizing the Christian's fight against paganism. At Bwlch Rhiwfelen (Denbigh) St Collen fought and killed a cannibal giantess, afterwards washing away the blood-stains in a well later known as Ffynnon Gollen. In Ireland, the tales of saints slaying giant serpents may have the same meaning; alternatively they (or some of them) may refer to early sightings of genuine water monsters. St Barry banished a serpent from a mountain into Lough Lagan (Roscommon), and a holy well sprang up where the saint's knee touched the ground.
Only hinted at in some of these tales, and clearly stated in others, it is apparent that there was a long and continuing conflict between paganism and Christianity in the early centuries A.D. This may also be the explanation behind other well creation tales, such as the slaying by St Barry of a 'great serpent' in County Roscommon. The saint thrust his crozier at it before it disappeared into Lough Lagan, and where his knee touched the ground, a holy well, Tobar Barry, sprang up. Although the serpent may represent paganism, and the saint's victory is therefore the victory of Christianity over paganism, we cannot entirely ignore the possibility that some of the serpents in similar Irish tales may have been real water monsters, which are still seen from time to time in the lakes of Ireland and Scotland. These eerie, ugly monsters, with their aura of primeval mystery, appropriately symbolize the uncouth savagery which the Christians attributed to all non-Christian beliefs; but that is not to say that the monsters were totally symbolic and did not have a reality of their own.