An important feature to note reading any poem within Songs of Innocence and Experience is that it allows the marginalized figures of society a voice. A voice in which their story can be told. Innocence would seem to the be the more controlled,ignorant perception of the truth. Whereas Experience breaks down Songs of Innocence and shows the real horror of the situation.
Blake does this brilliantly by the use of contrast and it is when the 'sister poem' in Songs of Experience is read and that voice of the truth comes through - it forces you not to ignore it. Where the two books come together and promptly force the reader to see the truth and not revert back to ignorance.
In terms of imagery,the idea of Innocence is strong in reference to children which then comes back to the point of the marginalized figures. As children were a strong labour force within factories working under dangerous conditions and treated and slaves in poverty. Blake also uses natural images such as flowers in his poetry. Which in the grand scheme of things represents the children. The bright,young and fragile beings who are being smothered in the cold,dark smoke of London town. This all brings into terms the idea of death.
Songs of Innocence almost grounds the reader into a state of security. Secure in the sense that we are living in a model society that is prospering and above all others. Yet,Songs of Experience destroys that foundation and pleads for us to do something about it. A scar which demands healing.