In the poem 'The Hidden Chamber,' is there anything that is actually hidden?

The poet tells the reader not to be afraid of the ghosts in the house. He openly admits that they are there, so their presence is not hidden and there is nothing to be afraid of. There are no animals in the house, and when a butterfly came in he let it go. The poet also tells us that there are no hidden rooms, hidden blood or hidden dangers to be worried about. However, he does say that there is a space without a door, or a locked room that isn't actually there. This is ambiguous. It is unclear whether there is something hidden, or whether there is just nothing there at all. It seems as if the hidden thing is not anything physical, but the hidden feelings and memories inside the poet. The 'hidden chamber' seems to refer to the part of his heart that he is not willing to share.