One of the things everyone knows about Irish mythology is that the deities we all know (Brigit, the Dagda, Boand, Ogma, etc.) are all members of the Tuatha de Danann, the people or tribe of the goddess Danu.
However, none of the Irish sources mention this goddess, who was an important enough ancestor that her name identified all of her descendants. (Imagine if the Olympian gods of Greece were known as the Gaians, for example.) Some Celtic scholars have gone so far as to doubt the existence of any such deity. Why?
The imagery of the Greek Gorgon can be traced back to Persian and Near Eastern art, but the myth of the beautiful Medusa seems to come from a different source. A story found in various forms in Greece, India, Ireland and Wales tells of a woman who either becomes a horse or has a strong equine connection, gives birth to twins and suffers greatly.
However, Demeter, Saranyu, Macha and Rhiannon are goddesses, while Medusa is considered a monster. Still, her story is so similar to these others that it obviously descends from the same Indo-European myth.
Human rulers die, and the next generation takes over. Sometimes the older generation gets “helped” off the throne, either by assassination or war. So it’s not surprising that mythology has many versions of this succession story, which rarely involve peaceful inheritance.
The Norse sun-goddess, far from being some sort of Northern aberration, is very similar to other Indo-European sun deities. This shouldn’t come as a surprise, since “basic” deities like the sky, earth and rivers tend to keep their characteristics across a very wide swathe of Europe and Asia.
The Irish goddess Brigit and the god Lugh have a great deal in common. Both have a triple form, both are powerful at every level of society, and both have a major calendar holiday associated with them. In the myths of the war between the two groups of gods, they have family on both sides.
What do the Egyptian god Horus and the Norse god Odin have in common? Both of them are said to have the sun and moon as their eyes. The difference is that this belief about Horus dates back to very early Egyptian religion. As far as I can tell, the same statement about Odin comes from some 19th and 20th century writers.
These Greek, Nordic and Celtic gods may not seem to have much in common at first glance, but they resemble each other in several ways, all of which illuminate aspects of their characters. All three are intellectual, associated with the arts, and have magical or oracular powers in addition to an unforgiving nature.
In Norse myth we have two stories involving the theft of a substance that confers a magical benefit to the user. Both involve the thief taking the form of an eagle. Both involve a pursuit with a god and a giant. Of course, the two myths have very different results, although in both cases the final score is Aesir 1, Jotunar 0.
One is the myth of the giant Þiazi kidnapping Iðunn to get the apples of immortality, the other is the story of how Oðin stole the mead of poetry from the giant Suttungr.