In human chemistry, Johann Eckermann (1792-1854) was a German author noted for being Goethe's verbal secretary, of sorts, from 1823 until 1832, and joint-editor of his works thereafter.
In 1848, Eckermann published his conversations with German polymath Johann Goethe, which he later documented in Conversations with Goethe (1836-1848).  Eckermann, it seems, did not become acquainted with Goethe until 1823. Specifically, in 1822, Eckermann wrote a Poetry with Special Allusion to Goethe, whose manuscript he sent to Goethe in Weimar. Goethe, age 73, then visited Eckermann, age 31, after which it seems Goethe hired him on as an organizational aid and sort of confidant.  To Eckermann, Goethe entrusted the publication of his Nachgelassene Schriften (posthumous works) (1832-1833). He was also joint-editor with Friedrich Riemer of the complete edition of Goethe's works in 40 vols. (1839-1840). 
On 06 May 1827, Goethe commented to Eckermann the retrospect weight of his Elective Affinities in his mind: 
“The only production of greater extent, in which I am conscious of having labored to set forth a pervading idea, is probably my Elective Affinities.”
On 18 Jan 1827, in conversation with Eckermann, Goethe discussed a letter from Solger to Tieck in which kind words about his Elective Affinities were spoken on the fine nature of the Architect’s character. Goethe commented on this letter that: 
“These remarks were written as early as 1809. I should then have been much cheered to hear so kind a word about the Wahlverwandtschaften; for at that time, and afterwards, not many pleasant remarks were vouchsafed be about that novel.”
Goethe commented to Eckermann, at the end of his life, that:
“I lived every word of my Elective Affinities.”
1. (a) Eckermann, Johann. (date). Conversations with Goethe (Gespraeche mit Goethe). Publisher.
(b) Goethe, Johann, Eckermann, Johann E., Soret, Frederic J., and Oxenford, John. (1883). Conversations of Goethe with Eckermann and Soret
(vouchsafed, pg. 205). G. Bell & Sons.
2. Johann Eckermann - Britannica, 1911.
3. (a) Tantillo, Astrida, O. (2001). Goethe’s Elective Affinities and the Critics (pgs. 154-57). New York: Camden House. .
(b) Eckermann, Johann P. (06 May 1827).
4. Johann Eckermann (German → English) – Wikipedia.
● Johann Eckermann – Wikipedia.