Though people sometimes refer to “images” in poems, a word is not the same thing as a picture. Words refer; images represent. When poets use nouns or phrases referring to something that an artist could represent by graphic means (a painting or sketch), they use them either for descriptive purposes or as illustrative examples. The images can be either literally pictorial (“This is the forest primeval”) or figurative, as when Wordsworth says of a young woman that she is “A violet by a mossy stone, / Half hidden from the eye.” Shakespeare’s three images in Sonnet 60 for time’s action (ocean waves; a sun that rises and is eclipsed; a repeated destructive attack by a spear, a spade, a maw, a scythe) give three illustrative ways of thinking about life: life is a steady state in which each moment, wavelike, resembles the next; or, life is a glowing rise followed by a catastrophic blackout; or, life is experienced as a continuous and premature and universal execution. These are not compatible images, and the poem makes us see each later image obliterating the former model(s).
Images, in fact, serve in poems as a shorthand for argument. It is quicker to show than to tell. It is a rule of thumb in poems that when a second, different, image follows a first, the second one is somehow importantly supplementing, or indeed correcting or supplanting, the first, because of some perceived inadequacy in the first image (otherwise, the poem would not have needed the second). So, when William Blake wanders through London despairing at the evils of modern life, he first mentions, as a major evil that comes to mind, “the mind-forg’d manacles” of false beliefs. But he does not stop there. He replaces the manacles with the institution that imposes them, and that permits the exploitation of the poor and the powerless — the Church. Yet the Church is not the worst evil: after all, to lose one’s life is worse than to be manacled in mind or to be poor, and so Blake goes on to indict the monarchy, which sends its sons off to be killed. Yet even that image of evil does not suffice. He must supplement Church and Palace with one more, the worst — the corruption of the sexual life which, by prostitution and syphilis, blinds the newborn infant in the cradle. Blake’s images rise, supplementing and even replacing one another, to the fatal last word in the last line:
I wander thro’ each charter’d street,
Near where the charter’d Thames does flow,
And mark in every face I meet
Marks of weakness, marks of woe.
In every cry of every man,
In every Infant’s cry of fear,
In every voice, in every ban,
The mind-forg’d manacles I hear.
How the Chimney-sweeper’s cry
Every black’ning Church appalls;
And the hapless Soldier’s sigh
Runs in blood down Palace walls.
But most thro’ midnight streets I hear
How the youthful Harlot’s curse
Blasts the new-born Infant’s tear,
And blights with plagues the Marriage hearse.
It is necessary to see the climactic order of Blake’s images (“But most . . . I hear”) in order to set them in relation to each other. Every image needs to be related to others in the same poem, but in an imaginative, not a mechanical, way. You need to enter the mind of the speaker, make yourself into the speaker, and ask yourself how you are connecting things in your ongoing expression.