Written by American expatriate Ezra Pound, Hugh Selwyn Mauberley showcases the poet's disappointment that art has lost its meaning in this modern, "savage," post-war world.
Pound introduces Hugh Selwyn Mauberley, the speaker of the poem, as his alter ego: a poet that represents his own personal views and opinions about art, poetry, and the art of poetry, or perhaps someone who represents an entire generation of modernist poets and artists who have lost their artistic vision and became victims of materialism and greed. The tone of the poem therefore, is elegiac and nostalgic, but also bitter and critical.
Pound implies that it is impossible for an artist or a writer to create meaningful and beautiful art in a world that is obsessed with money and power. He argues that the Greeks and the classicists might've been the only ones who truly appreciated art in its most raw form, while the contemporary artists and writers don't really care about the craft and only create art to make money, which defeats the true meaning and purpose of art and literature.
In fact, Pound created Mauberley for this specific reason: to express both his nostalgia for the past and his bitterness and hopelessness. Mauberley is nostalgic and sad, and Pound satirizes his nostalgia, expressing his anger and disappointment toward the modern society and its treatment—or rather mistreatment—of art and literature. Thus, the tone is also satirical.
The creation of art for art's sake—the enjoyment that comes with freedom of expression and having no limitations or constraints—is essentially the main theme of the poem, and the exploration and rediscovery of the purpose and nature of art is the poem's central question and idea. In this context, Hugh Selwyn Mauberley is an elegy for art and a critique of the modern, materialistic world.
You can read the full poem and understand its tone, context, and central questions here.