What was the earliest diary by a European poet, dramatist or novelist?

Question

The earliest surviving diary by a poet is probably the Tosa Diary by the tenth-century Japanese poet Ki no Tsurayuki. More details about this diary can be found on the Diary Review blog.

The Diary Review blog has several blog posts about European diaries from the 1500s and earlier, but none of the authors of these diaries were literary figures (although some of them published non-fiction). There is, of course, the famous "diary" of Philip Henslowe (that is, "famous" among scholars of English Renaissance drama), but this is really " collection of memoranda and notes that record payments to writers, box office takings, and lists of money lent" (Wikipedia) and not a diary in the usual sense of the word. In addition, Henslowe didn't write any literature.

The diary of Richard Torkington's pilgrimage to Jerusalem in 1517 was for some time believed to be the oldest diary in the English language; its first editor, William John Loftie, give it the title Ye Oldest Diarie of Englysshe Travell. The Pilgrim Libraries project has identified a number of older accounts of pilgrimages, usually written afterwards rather than during the voyage, and none of them by literary figures. In English, one of the most famous diaries is probably the one by Samuel Pepys, who was a civil servant and politician rather than an author of fiction.

The above paragraphs represent the results of my searches so far, which have been unsuccessful. I am looking for the earliest surviving diary by an author of poetry, drama, stories or novels, not treatises, translations or pamphlets. The author should primarily be known as an author of poetry, drama, stories or novels, ideally published (or circulated in manuscript form) during their lifetime, but since some people think that "primarily known as ..." is a matter of opinion (e.g. is X better known as a poet or a diarist?), this is only of secondary importance. I am curious to find out whether it says anything about the author's ideas about his craft.

Answer 1

When I posted my question, I assumed that there would be some diaries by 16th-century authors of fiction, but I have not found anything that fits these criteria so far.

In France, the Journal d'un bourgeois de Paris is a sort of chronicle or diary by an anonymous Parisian written between 1405 and 1449. In Italy, Luca Landucci (1436–1516) kept a diary that is an important source of information on daily life in Florence, but he was an apothecary, not an author. In England, John Dee (1527 – 1608 or 1609) kept a sporadic diary in the years 1577 to 1601, but he was not an author of fiction.

The French Wikipedia article journal lists examples of diaries, starting in the seventeenth century. The earliest European author listed there is the French novelist Rétif de la Bretonne (1734 – 1806). The English Wikipedia article does not mention his diary; the Société Rétif de la Bretonne has a list of the author's publications that shows that the diary ("journal intime") coverin the years 1780 – 1787 was published as Mes inscriptions in 1889. (The original cover actually used the spelling Mes inscripcions.)

However, Johann Wolfgang Goethe (1749 – 1832) kept a diary that started in 1775; see Goethe, Johann Wolfgang: Tagebücher on Zeno.org.

E. T. A. Hoffmann (1776 – 1822) also kept a diary, apparently starting in 1803.