Many years ago PBS ran a series of television shows about American poetry called Voices & Visions. Each episode focused on one great American poet, and I think that name, Voices & Visions sums up nicely what poetry becomes about for each of us who write it. Voice and vision share a symbiotic relationship within the work of each writer. Vision shapes the types of poems we write. Our voice as embodied in the poems hone and develop our vision.
As we write we think through our subject matter, embody that thinking in language, and shape it with line. Graham Wallas in The Art of Thought mentions a little girl who “had the making of a poet in her” because on “being told to be sure of her meaning before she spoke, [she] said, ‘How can I know what I think till I see what I say.’” Wallas seems to agree that poets think as they say. By giving our thoughts voice, our visions are refined and defined as our own. Poetry is an art where a solitary voice and our solitary vision fuse in the making of each poem.
The history of the lyric is filled with distinctive poems of the I; poet Gregory Orr suggests that every culture has a lyric poem because the human need to express the unknown and overcome chaos. To be able to put it into language and thus “order” feelings that overwhelm us is an inherent need. Consider how many people write when they are sad or depressed; or why when they’re ecstatic with love they write about it. There’s a reason why there are so many love poems, so many elegies, so many cliches about writers who are crazy: writing allows us to express and to edit (or, better yet) clarify exactly what we feel. Although long over, the Romantic era’s sensibility of the poetic I remains rooted, perhaps, in William Wordsworth’s notion that inspiration is found “in the spontaneous overflow of powerful feelings,” which the poet works on when he can “recollect in tranquility.”
It’s easy to think we must recollect accurately, after all novice writers are told to write what they know, but not how to leap beyond the self into the imagination. What we know only takes us to the edge of mystery. The next step is to envision what we don’t know based on the empiricism of what we’ve seen, what we’ve heard, what is possible. Novice writers are taught various forms but not how to use the poem to help them find their vision, how to use it to shape their voice. It takes time, truly, to discover the intricacies of poetry, to learn the various ways it might be used, and the various ways it helps us to formulate what it is we mean to say. That’s rocky terrain. It means we have to acknowledge that we don’t know what we want to say just yet, we have to begin in uncertainty, in a world that often seems filled with talking heads who seem so certain as to what’s right and wrong. That’s why it’s good to remember that we tend to learn more from our poetic failures than our successes.
We must also remember to trust the poetic process and our ability to actually find something to say. Writing in this way allows that voice and vision are interwoven. In one of the first books of literary criticism, The Literary Mind & The Carving of Dragons, the Chinese scholar Liu Hsieh notes that poetry is a combination of fruits and flowers. By fruit he means that what is said that is sustaining, in other words: content. Flowers refers to how content is said. A good poem has lots of fruit and lots of flowers, vision and voice. 
Louis Simpson in his essay “Honoring Whitman” notes that “[p]oets don’t have to be philosophers on the scale of Kant—they need only have ideas that enable them to make sense of their experience and make it seem worthwhile to go on writing.” More though, we have to express our vision in a way that makes it seem worthwhile for the reader to go on reading. Just as our experiences must be transmuted to be more than just the facts, so, too, must our voices be transmuted. It is important for poets to love language and its possibilities—the way certain syllables make our mouths move; the way certain sounds clash together while others blur into each other. The poet’s voice is a transmutation of our own, but heightened: not in diction, or in rhetoric, or in intelligence (a good poem does not drop SAT words will nilly) but in concern for the musicality and imagistic capacities of each word and in concern for the possibility of multiple meanings and ambivalences through an understanding of homonyms, connotations, and denotations.
This understanding, then, allows for some help with the “best words” part of Samuel Coleridge’s dictum that poetry is “the best words in the best order.” Our vocabularies surely reflect our poetic voices; ditto, our syntax and diction (our word order and how our words are used) shape our voice and tone (the attitude of the speaker toward subject matter). “High” language about base things can add sarcasm done well, or it can seem pretentious done poorly. Word order helps this. But order does not only include the ordering of words in our sentences, but the ordering of words in our lines. Our sense of line—of rhythm, of pacing, of its potential to make meaning, to create emphasis or surprise—is also part of our voice. As our sense of the possibilities of poetic craft develop, so too does our poetic voice.
To put it more simply: our voice is made up of our poetic vision, our sense of poetic craft, our love for language, our subject matter and our attitude toward it. With that said, whether we use the I or not, our poetic voice is an extraordinarily intimate part of our poetic selves. What develops as we develop a voice, is the lyric I who uses a private language for public discourse. By a private language I don’t suggest our words mean “differently” than the dictionary definitions, but rather our language is representative of our thinking, our private selves. It’s this intimacy that defines poetry as different from many pop songs, that seem to be very “public” in their sensibilities. And, when done well, the intimacy of a poem is its strength. Bly suggests “[p]oetry is best imagined as a conversation between two beings, even if it’s a conversation between body and soul. If two beings talk inside a poem, the reader usually has a chance to get a word in edgewise.”
What I like about this way of thinking about a poem is that such conversations require both a level of trust and a need to withhold. We trust that the poem is a safe place to discover what’s beneath our wanting to talk about a particular subject matter, and we can withhold everything that seems unnecessary or uncertain. Our poetic voices are means of exploring and defining (or constantly redefining) our visions and such explorations should also help our voices to evolve. For our readers, they become confidants in the dialogue, sharing in the experience of thinking, so that it becomes part of their thinking, too. But they have to be invited into that experience through the poem’s voice.
These first five paragraphs are a slightly variant version of comments on voice from LaFemina’s textbook Composing Poetry: A Guide to Writing Poems and Thinking Lyrically (Kendall Hunt, 2016)