I read a definition of the word "epiphany" in Merriam Webster Dictionaries which was:
An intuitive grasp of reality through something (such as an event) usually simple and striking
I wonder how how can something "simple" be "striking"?
You can think of an intuitive grasp as "an insight," which you can experience as simple (clear). Such insight may or may be not striking (sudden and impressive).
In this context, simple refers to "not complex," and striking to "attracting attention." There's no contradiction between simple and striking. For example, you can see a rock rolling down a hill, which is a simple and striking event, and you get an insight and invent the wheel.
Intuitive means perceiving directly by intuition without rational thought [and, therefore, perceiving it as "simple"] (Dictionary.com)