I know the expression "every cloud has a silver lining". I know its meaning, I know its origin, I know the meaning of individual words.
What I do not understand and failed to find an explanation for, is why would someone starts talking about a lining inside clouds. I assume the silver part is merely an analogy to the grey color of the clouds, yet if it is a lining, there is no reason for it to be visible on the outside. But what about the lining? In my understanding as well as the dictionary's (M.W.) a lining is what covers the inside of something.
How does that apply to clouds? Is it like pretending clouds are hollow? Is this about a sort of imaginary hidden treasure? I know the expression is not about a real physical lining, let alone silver made. But still, does a native English speaker understand easily how a cloud could have a lining or is the expression just taken as it is, without trying to parse it? Could someone please tell me what I am missing?
Stating the obvious, English is not my mother tongue.
Reply regarding an alleged duplication: my question is strictly about the possibility of a literal meaning to the expression, not its origin in a regular sense. I made it clear I knew both the origin story (Milton) and meaning (bright side).