I think the concept of truth has always been present even before we came to be. Thus an idea circling one's head can be described as truth even not at first being demonstrable, afterwards being worked on it can be shown. As proof there's the example of Einstein. At first it takes to approach it mentally, afterwards try and fail and at the end to succeed. That we can't see it in the first place and need proof doesn't take away the truth being there in the first place. It only confirms it.