Genuine question about the triple goddess post - I've read about female deities (in groups of three) appearing on ancient stones in Celtic parts of ancient Europe. Is there just no further evidence that they were venerated or is there another reason Celts don't have triple goddesses?
If you’re talking about the Mother cults it’s really difficult to say. A lot of times people will turn and claim this as backup to the existence of triple goddesses but there really isn’t a whole lot of evidence besides the depictions to back it up.
Honestly it hearkens back to Neolithic polytheistic practices but since it’s impossible to relate that in any way to the mythos of the Tuatha it’s not a strong ground to stand on.
I have mentioned this a lot, but there was a practice of doubling and tripling mention of goddesses (specifically Brighid) to denote how important they were, which can be (if read literally) confusing because you have a set of three sisters with the same name. Honestly it just shows status.
The only deity in the Gaelic sphere that could even potentially fall into a “triple” goddess form is Beara, the Scottish hag goddess who would age through the course of the year, grow old, go to sleep and re-emerge as a young woman again. But she is one single deity and there isn’t much about her. And I’ll note that Cailleach Bheur, the Irish goddess of similar persuasion does not do this at all. She prowls during the fall and winter, then sleeps for the rest of the year or retreats to the mountains until the year turns dark again.
Ultimately the Celts (using this in it’s proper context of an umbrella term) were pretty specifically hard polytheists. Their gods walked the earth, they weren’t nebulous concepts of power and affluence. To that end, it’s not a logical jump for this 3-in-1 business. If you wanted to read up on that, googling Robert Graves and the triple goddess will lend you some perspective. He basically invented the idea.