Gunn’s poem centers on comparing the artificially composed troupe of bikers and the flocks of birds he sees wheeling through the sky. The birds have a natural dignity and pursue an uncomplicated agenda, driven by primal instinct and uncomplicated by the ambiguities of language. 

On the other hand, the bikers are clumsy and violent in their pursuit of freedom. Their passage disrupts and destabilizes the world around them. They compulsively move onwards without any clear idea of their motivation or final end. The poet’s human rationality and command of language remove him from the instinctual animal world without lending him the transcendent certainties of the religiously-informed past – of the “saints."

The central philosophy of Gunn’s poem is inspired by his reading of existentialist thinkers such as Sartre and Camus. Gunn’s bikers are cut off from both the easy instinctual spontaneity of the natural world and the spiritual certainties of the past – they are neither “birds” nor “saints.” Their untiring pursuit of an elusive, transcendent ideal ultimately becomes meaningful in itself. They lend meaning to their own existence through movement, however fundamentally meaningless that movement might be.

All dressed identically and moving in formation, the gang assumes a collective identity and symbolic meaning that transcends its individual members. In a world where religious communities have lost their meaning, this kind of manufactured belonging is emblematic of humanity’s ongoing quest for meaning. 

The bikers are a disruptive, negative force in the world around them, scattering the birds whose harmonious, spontaneous formations inspire the author’s musings in the first stanza. They are introduced as “the Boys," an epithet that stresses their unity, naiveté, and youthful vulnerability. Their position astride their motorcycles is described in a sexualized, sensual language, which again suggests both erotic allure and vulnerability.

Gunn wrote the poems collected in The Sense of Movement shortly after moving to California to be with his gay partner Mike Kitay, and the poem is, in many senses, a reflection on his own homosexual identity. The poet is clearly deeply attracted to “the Boys” in the motorcycle gang, even while perceiving their flawed human nature, fragility, and vulnerability. 

The bikers all rise up in the dust like carrion flies, scattering the birds whose peerless, natural order was admired at the beginning of the poem. The poet’s erotic attraction to the bikers goes against the conventional morality of Judaeo-Christian traditions, as personified by the “saints” of his poem. It is also less straightforward than the animal instincts spontaneously pursued by the “birds.” 

The irresistible allure of the “Boys,” despite the difficulties it represents, is a fundamental component in the existential momentum affirmed by the poem as a whole. Interestingly, in his 1952 essay Saint Genet, Comédien et Martyr, Sartre identifies Genet as an existential hero precisely because his homosexuality went against conventional customs and traditions, constituting an act of personal, wilful rebellion against the prevailing social order.