I must admit that although it has felt that way to me, mine have been small -- figuring out a crossword answer, or how the evidence in a case tied together to show what happened, or why someone was behaving in a way that had seemed mysterious.

I guess this qualifies...
I like to look at the sky. Especially clouds. One day, while watching a sky full of individual puffy clouds, it was like someone suddenly flipped a switch in my head and I was now seeing the clouds, and the entire sky, as 3-dimensional objects, hovering hundreds/thousands of feet overhead, receding off into the distance. I guess I had all my life just "saw" the sky as this flat blue plane and had never really observed the depth of it all. It was, as you say, an epiphany.

I had a pretty useful one a few years ago that still bears fruit.

I'd spent most of my life thinking that my emotions influence my thoughts. When I was sad, there was nothing I could do about the sad thoughts in my head.

I realized via some reading I was doing that the opposite was, in fact, true. I found that if I stopped thinking sad thoughts, I could alter my emotions. It was incredibly empowering.

I'm still bummed out or pissed off sometimes, but at least now I know I can stop it if I want to. WAY BETTER.

Don't you get one of those when you're having a baby?

It was an epiphany for me when I realised that I didn't, after all, have to have any dealings with my sister. After years of her manipulative, lying behaviour, I decided that I'd had enough. She's a totally selfish person without a shred of decency or compassion. There was a final, awful event that was the last straw and I thought "I'm done with you". And I was.

That was nearly 3 years ago. Oh, my life has been so much more serene since then.

Yeah, I had one that resulted in an entirely new career direction and really strong focus on what I wanted to do. I remember the moment it hit me, and a year or so later I had moved states, moved jobs, and started out on the path I'm still on and very satisfied with.

Don't you get one of those when you're having a baby?

Not if it's a crustacean birth.

LOL, made my day