As we saw in the General Introduction, there is a subtle difference between the German verbs erklären, ‘to explain’ or ‘explicate’, and erläutern, ‘to elucidate’ or ‘cast light upon’. The natural scientist explains the phenomena that he observes, the human scientist (in Dilthey's terms) elucidates his. The first verb implies tangible data and positive methodologies, measurement and quantification, the second implies vague subject matter and imprecise methodologies, surmise and conjecture. As to the outcome of these processes, Erklärung implies something concrete – the interior workings of something fully accounted for –, whereas Erläuterung implies something less committal – an essence glimpsed, a meaning adumbrated.

To present-day music-theoretical ears, the term Erläuterung has strong associations with Heinrich Schenker, whose Erläuterungsausgaben, ‘elucidatory editions’, of Bach's Chromatic Fantasia and Fugue in D minor and Beethoven's last five piano sonatas are familiar to theorists and historians. Significantly, those works were published in 1910 and 1913–21. The similarity between a public advertisement of 1921 for the second of these and the title of a quite different volume from 1910 (my italics) – just one of many volumes published around the same time – is striking: