National Literature Prize winner in 1935. Between 1936 and 1939, he fought on the Republican side and, at the end of the Civil War, went into exile, first in Mexico and later in the United States, where he worked as a literature professor at several universities.

The Sphere, a novel somewhere between the lyrical and the philosophical, is a book that, in constant evolution, was written and rewritten over the years, as a compendium of existentialist reflections. Published in 1939 in Mexico, in 1947 in Buenos Aires, and, in a third and final edition, in 1969 in Madrid, the author takes the opportunity to address his readers through a note on the first page in which he states, in response to the speculation that his interpretation had been arousing, that he prefers not to clarify the novel's intentions and considers it better to "leave (it) in the semi-secrecy of poetic forms."

Those who have studied the Aragonese author's work in depth affirm that this is his most ambitious book, although paradoxically it is also his least known.