I looked online for the meaning of the expression "Can't see the wood for the trees"; see for example, this. It means getting so much involved in the details of something such that you can not see the whole picture/view of it.
I am wondering why? How does the connection between wood and tree imply this?
PS: In a similar expression "can't see the forest for the tree" with the same meaning, it makes sense to say looking very closely to trees prevents somebody seeing the whole forest. In other words, looking closely to the trees is the reason ("for" word in the idiom) that somebody might not be able to see the whole forest. But I can not see such a connection between wood and tree in the expression "Can't see the wood for the trees"!