She's remembering a time when the place she was standing in was in the woods, just nature with nothing manmade about it. And the wood thrush used to sing there. But now the woods have been cut down to make way for buildings and pavement and roads, and the wood thrush has gone away with them. The wood thrush represents everything pure about nature. And the singer is contrasting that purity with all the things people do to "improve" the world for ourselves. She points out that no matter how much we know and seek to understand, no matter how much humans learn and think we know, we will never understand anything as basic and natural as the way a wild bird sings. And now that the woods have been cut down to make way for progress, all she wants is to hear the wood thrush sing again, to have things be how they were before, in a more innocent time.
She's remembering a time when the place she was standing in was in the woods, just nature with nothing manmade about it. And the wood thrush used to sing there. But now the woods have been cut down to make way for buildings and pavement and roads, and the wood thrush has gone away with them. The wood thrush represents everything pure about nature. And the singer is contrasting that purity with all the things people do to "improve" the world for ourselves. She points out that no matter how much we know and seek to understand, no matter how much humans learn and think we know, we will never understand anything as basic and natural as the way a wild bird sings. And now that the woods have been cut down to make way for progress, all she wants is to hear the wood thrush sing again, to have things be how they were before, in a more innocent time.