Edwin Muir's poem, “The Gate,” not only marks literally the dividing point in his work between almost unrelieved darkness and increasing light, but, in every detail of its complex structure and in controlling metaphor, it signals the loss of innocence, the intimate acquaintance with evil, which Muir's later poems suggest must be endured before there can be any true knowledge of good. Both halves, into which the poem is cut by a strong caesura in the twelfth line, plunge in parallel downward movements from security into loss and fear; and although a secondary movement, based on a metaphor of initiation, carries the poem forward, over the threshold of “The Gate,” this forward step also turns out to be downward. Because of Muir's persistent association of a castle with treachery from within, as his novel, The Three Brothers, and several poems show, the step into the fortress of adulthood is simultaneously a drop into the central darkness and terror of the universe.