Here's a little insider's tip: "Tell All the Truth But Tell it Slant"? That's not really the title. This poem doesn't actually have a title. In fact, none of Dickinson's poems do. Since their discovery, editors have given the poems numbers in an attempt to organize them. They're numbered in the order they were supposedly written. This one's 1129 (bingo?). It's a little late in the poetry game for Dickinson. Like many critics and publishers, we now let the first line of the poem do double duty as the title, too. And what a good duty is does, right? That first line really just sums up the crux of the speaker's argument. You've got the main idea packaged right there for you, wrapped up and handed over on a silver platter before you even get to line 2. Now that's convenience.