1
general::
Be apparently unable to, as in No matter how hard I try, I can't seem to concentrate on this book. This phrase gives added emphasis to a negative statement, as in the example. [Late 1800s] can't see the forest for the trees Also, can't see the wood for the trees. Focus only on small details and fail to understand larger plans or principles, as in Alex argues about petty cash and overlooks the budget? he can't see the forest for the trees. This expression was al ready a proverb in John Heywood's 1546 collection.
American Heritage Idioms