along with the words and phrases I mention above, lead me to conclude that this poem provides the reader with the rider's destination: death.

The first stanza refers to a valley, which may allude to the line of the Twenty-third Psalm (in the Bible, perhaps also known to some as "The Lord is My Shepherd), "Yea, though I walk through the valley of the shadow of death..." "Furnaces burn" and "odours will madden" could easily refer to the sulfurous stench associated with Hell (the fiery "pit); and "midden" refers to a dung heap or refuse pile (trash). Bottom line, this may then be a warning to the rider (or "mankind," in general) to be wary of ending up in Hell. I can't be sure, be feel the "gap" may refer to the place that separates Heaven from Hell, and the "tall" may refer to the "upright" (righteous, God-fearing) who avoid Hell.

The second stanza is a question from the fearful one to the traveler ("farer"). The inquiry is whether the "dusk" (perhaps older age, or even moving away from the "light" or God) will delay the progress the traveler hopes to make. The "pass" may refer to the road that leads to heaven. "Diligent looking" may speak to the care the farer takes to remain on the "straight and narrow" path to God, which is necessary to avoid leaving the "granite" (solid footing) to end up in the "grass" (the easier road, but one that leads to Hell).

Moving into the third stanza, "horror" represents the fear many people have of dying. The "bird" could allude to a premonition of evil, such as the raven in Edgar Allan Poe's poem of the same name. "Twisted trees" could well speak to unnatural or ill-conceived things of this world that either cause fear or self-doubt to the lover of God. The "figure comes softly" certainly must describe man's personification of death, or the "grim reaper." "Spot on the skin" may literally cite a disease or metaphorically describe "sin."

The last stanza tells the farer that no one will never be able to avoid death: "Out of this house...Yours never will." Death is personified here as "...looking for you." Those delivering this frightful reminder are the rider, the farer and the hearer, speaking to the audience: referred to as the reader, the fearer and the horror. The message is almost debilitating to one who is afraid of dying (most of us, I expect), and perhaps Auden is trying to speak to all people.

However, there is a subtle shift in the last line that changes Auden's presentation of the Old Testament view of death—without hope, to new life: the reader leaves horror and fear behind, believing he will be saved by his faith.

Considering that W. H. Auden's poem, "O, Where Are You Going?" was written in 1931 lends an intrinsic meaning to this poem. For,  Auden was living in an America which was in the grips of the Great Depression, a fear of the rise of Fascism, and suffering from the fears, compromises, and cowardices of what Auden termed "a low, dishonest decade."  Auden, however, saw himself as "a beacon of light in the darkness," and the final stanza of his poem expresses this self-image.

The orators of the first three stanzas echo the hallucinatory fears and despair of this decade as under the beauty of the valley there is an evil lurking--"That gap is the grave where the tall return"; the twisted shape in the trees, the "figure [that] comes softly" and "the spot on your skin" are all bad things lurking under the normality of the appearance of things.  But, without the daring to experience and leave the despairing and fearful behind, there is no reason to live.