After a vague early intention of entering the priesthood, he attended law courses at Coimbra, where he devoted himself to a passionate study of progressive ideologies, with manifold interests in foreign cultures, German culture first and foremost. Having turned to socialism, he became its propagandist, and in 1890, with his poetry, his first book, "La poesia del socialismo" (1865), was published by "La Poesia del Socialismo" (1871), with the first of which he dealt a mortal blow to Romanticism (still flourishing under the guidance of the old blind poet Castilho), and with the second introducing into Portuguese life tendencies, tastes, and advances typical of the second half of the 19th century, with attempts to reconcile materialism and spiritualism. Among his most characteristic ideas was that of Iberism, i.e., a fusion of the two nations of the peninsula into a liberal republic. Bitterly disillusioned by the contrast between his ideals and everyday reality, gravely impaired in health by overwork and the intensity of his inner life, withdrawn into philosophical meditation in a pessimistic view of things, he committed suicide.
The poetry of Q., who, having lost his faith, still felt the need for one, achieves a singular transformation of a world of ideas into a world of art. The poet’s inner torment is soothed in his lyric verse, in crystalline and perfect lines, especially in his later compositions, those of the Odes modernas and, above all, of the Sostenes: he restored the sonnet to the heights to which it had been elevated three centuries earlier by Camões. Among his sonnets, famous are those in which there is revealed the poet’s longing for religiosity, sometimes even in a tendentiously Catholic sense: Ideal, A Virgem Santissima, Na mão de Deus.