"But for a few phrases from his letters and an odd line or two of his verse, the poet walks gagged through his own biography"

This quote by John Updike speaks to the difficulty of properly capturing the life of a poet in a biography. Updike suggests that the poet is "gagged" in their own biography, unable to totally express themselves in the way they would like. This is since bios are frequently limited to a couple of expressions from the poet's letters and a few lines of their verse. This suggests that the poet's life is not fully represented, as their bio is unable to record the full series of their ideas and feelings. Updike's quote highlights the problem of precisely representing a poet's life in a bio, as it is often limited to a couple of phrases and lines of verse.