One of the most famous poems by T. S. Eliot is ‘The Hollow Men’. One of the most famous sections of poetry in all of T. S. Eliot is the fifth and final section of ‘The Hollow Men’, which contains the famous lines, which state that ‘between the idea and the reality falls the shadow’. But what do these lines mean?
It’s worth briefly placing this reference to ideas, realities, and shadows in the context of the poem in which they feature. Eliot’s ‘The Hollow Men’ was published in 1925, seven years after the end of the First World War and three years after arguably his most famous poem, The Waste Land (itself partly a response to the recent war).
But whereas The Waste Land offered us a modern London in which people have lost their way – crowds of clerks commuting to work over London Bridge in some sort of stupor, typists having unsatisfactory romantic liaisons with estate agents on sofa-beds – ‘The Hollow Men’ leaves behind all traces of the modern world. Instead, we find ourselves in the desert wilderness that was glimpsed sporadically in The Waste Land: an arid land which has now become everything and is everywhere. The ‘Hollow Men’ of the poem are themselves trapped in some sort of between-world, a limbo or purgatory between death and life, existence and nothingness, light and darkness.
In five sections, Eliot lets the collective voice of the Hollow Men address us from their between-world which is at once a desert space (‘cactus land’) and a place suggestive of entropic decay, as though the end of the world or even the universe 
has come: that fading star, and the general lifelessness of the world the Hollow Men inhabit, imply that this land of twilight is a world in its death throes. And indeed, when we reach the final lines of the poem, we are told that we are witnessing the end of the world, which happens anticlimactically, with a whimper rather than a bang.
The fifth and final section of ‘The Hollow Men’ is a little different from what had gone before. For one thing, it is far more allusive: that is, it utilises far more recognisable literary allusions to other works. These include nursery rhymes (‘Here go round the mulberry bush’), the modernist author Joseph Conrad’ (‘Life is very long’ is from Conrad’s 1896 novel An Outcast of the Islands), and even religious scripture (‘For Thine is the Kingdom’ is from the Lord’s Prayer, which originates in the Sermon on the Mount in the New Testament).
But there is one less obvious allusion whose significance we might probe. For ‘between the idea and the reality falls the Shadow’, critics such as Christopher Ricks (in his excellent T. S. Eliot and Prejudice) have suggested, is an allusion to Brutus’ words in Shakespeare’s Julius Caesar:
Between the acting of a dreadful thing
And the first motion, all the interim is
Like a phantasma, or a hideous dream:
The Genius and the mortal instruments
Are then in council; and the state of man,
Like to a little kingdom, suffers then
The nature of an insurrection.
(And yes, the young-adult author Cassandra Clare took the phrase ‘mortal instruments’ from this same passage.)
Of course, Shakespeare gives us acting and motion, conjoined by that key word for ‘The Hollow Men’, between. Meanwhile, Eliot gives us between, action, and motion, and then act: the contrast is between conceiving an idea and acting upon it. And something falls between conceiving an action and actually going through with it: this mysterious ‘Shadow’. Just as so many characters in The Waste Land are paralysed or trapped in some form of stasis, so are the Hollow Men trapped, unable to act.
Of course, this final section of the poem begins with a song denoting action (a dance), but it’s a dance of repetition and pointlessness, at an ungodly hour, with no clear purpose to it. We then get a series of ‘between’ statements, which could not be more appropriate for this poem about interim states.
What is being described here? One possible interpretation is that Eliot is talking about that other interim state between death and life – not at the end of our lives, but at the beginning. Between the conception and the creation – what is a baby after it has been conceived but before it has been born? This is not to say that such an analysis of Eliot’s lines decides the matter once and for all, of course. But the fact that this series of ‘between’ statements, almost like a chant, is punctuated by a reference to life itself (‘Life is very long’) and to the words of the Lord’s Prayer (‘For Thine is the Kingdom’) suggest the almost divine miracle of human life.
However, perhaps we would be better off bearing in mind Brutus rather than foetuses, and think of Eliot’s chain of idea-reality-motion-act-conception-creation-emotion-response as referring to the complex relationship between our desires or aims and our actions and behaviour. The Hollow Men find themselves between the idea of escaping their existence and the reality of actually succeeding in escaping, but between that idea and longed-for reality the ‘Shadow’ falls which will prevent them from seeing their way to achieving their aim.