It has happened in the history of science that people found an elegant theory unifying seemingly disparate phenomena. Or, while learning a subject, it may seem

It has happened in the history of science that people found an elegant theory unifying seemingly disparate phenomena. Or, while learning a subject, it may seem really complicated and confusing, and later, once you have learned it, it may seem simple. But I'm not sure if you would count either of these examples. Can you provide a description of what a counterexample might look like even if it is made up?