The saying that someone “can't see the forest for the trees” is a reference to people who get so involved with the details of an issue that they lose sight of the larger issue. You may also hear it rendered as “so-and-so can't see the wood for the trees,” depending on regional dialects and personal preference. If you are accused of being unable to see the forest for the trees, you may want to take a step back from the situation to abstract yourself in the hopes that some clarifying and potentially interesting information emerges.

As early as the 1500s, "you can't see the forest for the trees" was in wide enough use that it was published in collections of proverbs and slang. As anyone who has been in a forest knows, it can be easy to fall into the trap of just looking at the individual trees, rather than considering the forest as a whole. When you can't see the forest for the trees, it means that you are deeply involved in a situation, and you are perhaps focusing too much on individual details, and not enough on the situation as a whole.

This proverb is also sometimes reversed, as in “he can't see the trees for the forest,” referencing the idea that it is also possible to be too broad when looking at a situation. Someone who makes sweeping pronouncements without considering the details could be said to be exhibiting just as much of a logical flaw as someone who focuses on a minute aspect of a situation without examining the whole. It is common for executives to be accused of not seeing the trees for the forest, especially when they make exacting and impossible demands which suggest a complete unfamiliarity with the complexities of a situation.

It is very easy to get caught up in minutia of a situation, especially when you have been involved with it for an extended period of time, or when you have only been working on one aspect of a larger problem. Being aware of this tendency can make people better problem solvers, as they know that sometimes they can't see the forest for the trees, and that occasionally it is a good idea to talk with other people about the aspects of the project that they are working on, or to solicit outside advice about a situation to gain perspective.

Striking a balance between focusing on the details of a situation and looking at it broadly is important. To take the metaphor further, when you can't see the forest for the trees, it suggests that you may be missing crucial information which may be influencing the situation, like why the trees are there in the first place.