This poem opens with a directive to the reader, which seems to frame the poem as instructions for writing poetry. Dickinson says to only tell the truth, and to tell all of the truth (“Tell all the truth”), but to come at it from an angle, not directly (“but tell it slant –“). “Success” in presenting the truth only comes when it is done circuitously (“Success in Circuit lies”).
This is because, Dickinson says, the surprising quality of the truth (“The Truth’s superb surprise”) is too overpowering for people’s weak perceptions (“Too bright for our infirm Delight”), thus they either would not understand it or would be overwhelmed by it. Thus, as the magnificent but fearful lightning is explained to children, to lessen their fear and awe (“As Lightning to the Children eased / With explanation kind”), so to should people be presented with indirect presentations of the truth, before they can see the truth itself (“The Truth must dazzle gradually / Or every man be blind –“).
Dickinson is highly interested in truth throughout her poems; it is a theme that she returns to repeatedly. Even in those poems where she does not deal with it directly, it is still there as an aim of the poem—to find and tell the truth about whatever that poem’s subject might be. Thus, “Tell all the Truth but tell it slant –,“ can really be seen as her overarching philosophy on poetry; her own, and her recommendations to others for their poems.
This poem makes the assumption that the poet knows the truth, but makes an active choice to hold it back, to “tell it slant,” so as not to dazzle the sensitive reader. In Dickinson’s poems, however, it seems more likely that her circuitous paths to the truth, returning to the same themes again and again, from different perspectives, with different metaphors, coming to different conclusions, are not so much to protect the reader from the pure light of the truth, but are because this is how she discovers it.
For her, the circuitous path is a circling round the truth in an attempt to find it and to guide others to it. This, then, makes the process of discovering and displaying the truth one and the same. Her paths lead her gradually to the core kernel of the truth, and the reader follows along that same path with her, which allows for a much fuller ultimate understanding of the truth than if Dickinson were to just tell it directly.
This poem, even if it is not only dealing with poetry, but any process of truth-telling, places poetry on a higher plane than other forms of art or communication. For poetry, whether it is Dickinson’s own or anyone’s, embodies this process exactly. Metaphors, allusions, imagery, and all the tricks of the poetic trade serve to present the truth to the reader without just saying it point blank. They are the “slant.” And this poem specifically embodies this, using multiple metaphors (truth as light, instructing or truth telling as physical travel), images, and a predominant rhyme scheme.
This poem, though, does leave some doubts as to how honest this “slant” truth-telling really is. In the second line, “Success in Circuit lies,” “lies” clearly has the primary meaning that success is found in circuit, however, Dickinson chooses every word very carefully, and the secondary meaning of “lies,” that is, dishonest statements, would not have been unintentional. In addition, the metaphor of using “kind” explanations to appease children is not quite apt, because these explanations often move quite far from the truth, whether for simplicity’s sake or because the truth is too disturbing.