José Martí wrote the Versos sencillos in 1891, ill and resting in the Catskill mountains, at a low point in his life in exile. He made them, he says, in octosyllables — the plainest, most singable measure in Spanish — and that is why they are "sencillos", simple: not poor, but bare. Martí was the great poet and the great prose writer of Spanish American modernismo, and also the man who organised Cuba's war of independence and died in it, at Dos Ríos, in 1895.
Poem I is a self-portrait. "Yo soy un hombre sincero / De donde crece la palma" — I am a sincere man, from where the palm grows: a man of Cuba who, before he dies, wants to cast the verses of his soul. The stanzas that follow are separate scenes — the wounded eagle, the child stung by the bee, the friend he prefers to gold — and each quatrain stands on its own, like a proverb.
That is why so many of them left the poem and set off on their own: the song Guantanamera is built from quatrains of these Versos sencillos, and countless people know "Yo soy un hombre sincero" without knowing whose it is. It is what Martí wanted: verses that would be sung.
The verse is kept in Spanish. Translating it in passing would replace the work with a paraphrase of it.