In 1978, Jon S. Vincent, then Associate Professor and Associate Chairman of the Department of Spanish and Portuguese at the University of Kansas, published his critical survey (in English): João Guimarães Rosa . In his preface he writes: “It is no doubt excessive to preface a critical study with the admonition that readers of the study take the time to learn another language before proceeding further, but I know of few writers more worthy of that effort than Guimarães Rosa.” I can affirm: it’s worth it. A year or so ago I set out to learn Portuguese in an effort to more closely approach Grande Sertão: Veredas. I understand that even among Lusophones an approximate reading is, in many cases, the most a first-time reader of Grande Sertão: Veredas can ask for, so I don’t worry that I’m too (too) far behind.
Besides being able to read GS: V (relatively speaking), I can also now take advantage of the abundance of literature by and about the author available in Brazilian Portuguese. For example, this:
In 1983, Vilma Guimarães Rosa, João Guimarães Rosa’s daughter, an author in her own right, published Relembramentos: João Guimarães Rosa, meu pai  (Remembrances: João Guimarães Rosa, My Father), which includes an interview she gave to Brazilian writer and journalist, Suzi Frankel Sperber. The following is one question and response from that interview, translated by myself.
[Keep in mind that João Guimarães Rosa spoke six languages and read in fourteen.]
Suzi Frankel Sperber: Why did your father dedicate himself to the study of languages other than our own?
Vilma Guimarães Rosa: [It was a result of his] desire to learn as much as he could. He was fascinated by the word and logos. He devoted himself to the study of our language, and always expanded, from a very early age till late in life, his interest in philology. Language is the means of expression. Man, fundamentally, is always the same, everywhere. But languages abound. The basic emotions are equal; the expressions are different. And therein lies the will to investigate them. To discover new values, to inquire into the possible affinities in the essence and sonority of words. Papa studied countless languages. He was an artist who familiarized himself with the tools of his trade. Here I am reminded of the extreme care he took in maintaining vast correspondences regarding the translation of his work. He maintained frequent contact with his translators, discussing page for page, suggesting lexical or syntactic alternatives more faithful to the transposition of his thoughts and intent, and proposing substitutions for words. [He served] an aesthetic function as well, in the verbal music. Euphony. […] His correspondences also reveal that in his study of foreign languages, a superficial knowledge of speaking well, of writing fluently in the most commonly accepted expressions would not suffice. He sought out the intimacy of words, the idiomatic spirit. As if each language was merely a part of the complete philology he so loved.