Archibald MacLeish's poem "Ars Poetica" literally means that a poem should be like things in real life, material life, which appeal directly and powerfully to our senses. We should feel, hear, see the poem in the same way we see and experience the things of the world. A poem should not be a theory, or an idea, or be written to carry a message any more than an apple carries a message. By writing this poem, MacLeish aims to remind the reader that a poem is a living entity, not something to study for a test or paper, not something to tear apart to find its "meaning."
The poem's figurative language is meant to bring the poem to life by appealing to the senses. The clarity and precision of the similes make the reader for a moment believe that he or she knows what the poem "means," but what is actually happening is that the poet is simply taking the reader deeper into the mystery.
The first three images of the first stanza bring to the reader's senses an experience of touch---the fruit described as if it were in the reader's hand, the reader's "mental thumb" moving over the features of the medallion, and the reader leaning out of the window in the old building to touch the cool moss-covered stone. Then, in the fourth image, the reader watches as a flock of birds takes wing---the poem (or at least the stanza) has already started to leave the reader behind with his "palpable" sensations and his emotional memories of the images.
"A poem should be palpable and mute/ As a globed fruit." MacLeish is concerned here with having the reader remember as clearly and substantially as possible the sensation of holding an apple in the hand (or whatever fruit is brought to mind). We almost hear the word "apple" in "palpable." We feel the apple as a living entity in our hand---"mute", which implies that it could speak if it wished, that it has the power to make us expect it to speak---and speak it will when we bite into it. Its roundness is emp...