Change is an important theme in the poem. The poem is based on an allusion to the second coming of Christ as predicted in the Bible. (Matthew 24). The atmosphere of imminent change is established from the beginning. The opening image is of a falcon (a vicious bird of prey) Its flight symbolizes cycles in human history.
As the falcon circles in an ever— widening gyre and spins out of control, "the falcon cannot hear the falconer". There is chaos and anarchy, as "things fall apart" and "the centre cannot hold." Images of doom follow in quick succession; first, there is confusion everywhere "Mere anarchy is loosed upon the world" and then wars: "The blood dummed tide is loosed" The changes are for the worse. Even the behaviour and attitudes of people undergo adverse changes —"The ceremony of innocence is drowned" as civilized behaviour is pushed aside by uncouth behaviour. Now, even those who lead "the best", are no longer sure of what is right, while "the worst" have taken full control of the world. The second stanza affirms that what is being witnessed is the end of an era and the start of another "The Second Corning". The image of the sphinx-like creature reinforces this impression of change. But this change is shrouded in uncertainty.
The creature with the shape of a lion and a man's head awakening slowly from sleep with "A gaze blank and pitiless as the sun" affirms the uncertainty. It is coming as Christ did to change the world. Frightening as it looks, the creature will bring about a change which may be positive. As the "indignant desert birds "are being swept away and the symbol of Bethlehem looms large, one can only hope that the change envisaged will be peaceful; but the poem's end does not guarantee it. There is no doubt therefore, that change is an important theme in the poem.