The common English saying, not to see the wood for the trees, is
occasionally subject to misinterpretation. Firstly, the wood is a
wooded area, not the material trees are made of. When the saying says woods or forest, this is clearer. Secondly and more importantly, the meaning of the saying is that someone cannot see the whole wood, because he or she is only seeing the individual trees. The implication is that the subject is taking a reductionist view of something that needs to be viewed holistically. It's therefore curious to encounter the positive form of the expression - to see the wood for the trees - which I have seen recently in adverts as well as hearing it spoken. If you can see the wood, you can see it. The for in the negative form indicates the reason why the subject can't see the wood, and if they can see it, there's no hindrance for the for to refer to.
The question of sayings containing negatives being reversed also comes up in the case of the expressions not to give a damn (or a monkey's or tinker's cuss, a twopenny damn, or a flying fuck) and not to be able to care less. The intent of these sayings - as in the famous line from Gone with the Wind - is that the speaker will not waste the trivial effort mentioned on the matter, or that he or she cares as little about the matter as possible. However, many Americans these days use the expressions in a positive sense, saying I could give a damn or I could care less. These expressions, the latter particularly, seem to make little sense. If you care very little about something, and wish to be dismissive of it, why say that you could care less?