In Chapter VII, "Heraclitus," of A History of Greek Philosophy, Volume One: The Earlier Presocratics and the Pythagoreans, page 403, W.K.C. Guthrie wrote in 1962:
A discussion of the thought of Heraclitus labours under peculiar difficulties. His own expression of it was generally considered to be highly obscure, a verdict fully borne out by the surviving fragments. Both in the ancient and the modern worlds he has provided a challenge to the ingenuity of interpreters which few have been able to resist. Perhaps not altogether unfortunately, most of the ancient commentaries have perished, but the amount written on him since the beginning of the nineteenth century would itself take a very long time to master. Some of these writers have been painstaking scholars, others philosophers or religious teachers who found in the pregnant and picturesque sayings of Heraclitus a striking anticipation of their own beliefs. If the interpretations of the latter suffer from their attitude of parti pris, the former may also be temperamentally at a disadvantage in penetrating the thoughts of a man who had at least as much in him of the prophet and poet as of the philosopher.
There is, then, an army of commentators, no two of whom are in full agreement.
Leaving aside the question of whether Heraclitus is especially difficult to interpret, Mr. Guthrie rightly identifies three other crucial obstacles facing the Heraclitus scholar, paraphrased:
1) Detail-oriented academics lack the temperament to comprehend the essence of Heraclitus's philosophy, without which all of his statements must seem obscure indeed.
2) Philosophers and religious teachers tend to have rather large axes to grind, leading to the most remarkable misreadings, such as those neo-Platonists who argue Heraclitus never wrote "You cannot step in the same river twice" and denied he believed in eternal flux.
3) Many, perhaps most, of Heraclitus's text has not survived, and most of the ancient commentary about him that might have allowed us to reconstruct and understand that text have likewise perished.
German publisher Academia Verlag, in their commentary on Serge Mouraviev's massive ongoing project with them, Heraclitea, identifies another, rarely discussed reason for the wide divergence of interpretations among Heraclitean scholars:
. . . until now the Heraclitean corpus has never been published in its entirety. Previous editors disregarded many texts. Other texts remain inaccessible for the average reader because of the rarity of the books in which they can be found. The lack of a complete corpus is one of the reasons why the scholars' opinions on Heraclitus' ideas continue to be so widely and so wildly divergent.
These and other difficulties have inspired Monsieur Mouraviev to embark upon an eleven-year, twenty-volume writing project in which he proposes to collect in one place everything written about Heraclitus from 500 BC to 1561 AD, with criticism and analysis, and to attempt a reconstruction of the book itself. This is indisputably the most ambitious work of Heraclitean scholarship ever undertaken. Academia Verlag published the first volume of the series in 1999, six volumes so far.
After ordering them a few weeks ago, I bought them today from my local bookstore, Santoro's Books, to whom I have been shifting much of my book-buying business lately in an effort to strengthen my neighborhood.
It is because they are written in French that I have recently renewed my interest in multilingualism. For anyone interested in Heraclitus, Serge Mouraviev's project is too important to miss. French and Ancient Greek are the languages I will be starting with this year, with this very series in mind.
Oddly, I find even the mere single year of college French I took proves enough to follow about a quarter of the text, but I am sure the remaining three quarters will require more study than I have put into any language other than English.