can't see the forest for the trees

Cannot see, understand, or focus on a situation in its entirety due to being preoccupied with minor details. The way he's obsessing over one doorknob when we're renovating the entire house makes me think that he can't see the forest for the trees. You won't get a quick decision from Marie—that woman can't see the forest for the trees. I just feel like he can't see the forest for the trees on this project, since he keeps getting hung up on the most mundane details at the expense of our overall productivity.

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 already a proverb in John Heywood's 1546 collection.

Focusing on small details makes one overlook the large picture. John Heywood’s proverb collection in 1546 has it, “Ye cannot see the wood for the trees.” A modern twist was provided by C. S. Lewis in a critique of William Golding’s novel, The Inheritors: “All those little details you only notice in real life if you’ve got a high temperature. You couldn’t see the wood for the leaves.”