Actually, the old master had been reviewing his precocious treatment of death and transfiguration rather more recently. Late in 1946, he had come across Eichendorff's poem Im Abendrot (At Sunset). This tells of an inseparable old couple at the end of life's wanderings, gazing at a sunset and asking, "Is that perhaps death?" To suggest that the text struck a chord - in fact, an effulgent glow of E flat major - would, for once, seem the literal truth. Was not Strauss himself a weary wanderer still, self-exiled in Switzerland while he awaited the verdict of the tribunals on his apparent complicity with the Nazis, and tottering from hotel to hotel in the termagent wake of his other half?
What was it about Pauline Strauss that enabled him to bear her tantrums with imperturbable uxoriousness for 55 years? To friends who discreetly enquired, he was liable to reply flippantly that a wife who locked him in his composing studio at nine o'clock each morning was just the sort he needed. But when they had first become engaged back in 1894 - characteristically after a mid-rehearsal row in the Weimar Court Opera - she had been one of the noted sopranos of her generation, and for years after, the majority of his songs would be composed with her special qualities of tone and phrasing in mind.
But one suspects she soon came to symbolise for him something beyond an ideal performing partner. "If Richard, then Wagner; if Strauss, then Johann," the old put-down used to go. And it is easy enough to dismiss Strauss by and large as an epigone - a composer whose fabulous gifts of ear and technique enabled him to whip up a souffle of a style out of the choicest classical and romantic ingredients. Yet no one before him - not the Mozart or Wagner he venerated; not the great lieder composers, from Schubert to Brahms and Wolf, whom he succeeded; not the 19th-century Italian opera composers he conducted - had ever written in quite the same way, or with quite the same feeling, for the soprano voice.
Those long, effortlessly unfolding melodies, those silvery arcs of sound with their exquisitely placed efflorescences of decoration: if ever there were a Germanic art of bel canto, Strauss uniquely commanded its resources. And where he allowed this central lyric gift its head, in his greatest operatic scenes and orchestral songs, it proved to imply highly personal harmonic and textural procedures as well.
Not for Strauss the almost chamber-music manner of his greatest Austro- German songwriting contemporary, Gustav Mahler, in which the voice is often interwoven contrapuntally with a mere handful of instruments. In order to support, to highlight, to lift skywards his aspiring solo lines, Strauss requires the late-romantic orchestra at its most oppulent. Yet although the surface of his accompaniments may often ripple or rampage with an almost unprecedented proliferation of detail - a proliferation as intriguing to study in score as it is to take in by ear - the underlying harmonies are likely to prove as unhurried in their progression, as masterly in their long-range reach and grasp, as the over-arching melodies on top.
No wonder he fell upon Im Abendrot as a consummatory emblem of his life and art. Admittedly its composition was to be interrupted by the sad necessity of having to copy out some of his earlier masterpieces as saleable manuscripts to set against his hotel bills (in the post-war imbroglio, his royalties were frozen) and by the rather more hopeful 1947 Strauss Festival in London that Beecham organised towards his rehabilitation. But on 6 May 1948, in Montreux, the setting was finished: a lingering, eight-minute fade- out with Eichendorff's last line - pointedly altered to "Is this perhaps death?" - answered by a nostalgic horn echo of the theme of youthful idealism from Tod and Verklarung, and the orchestra then sinking into one of those strange, inert harmonic textures with which Strauss could almost make time stand still.
Was he going to leave the setting on its own? He had, in fact, composed quite a number of earlier orchestral songs, either as original scores or by orchestrating lieder he had first published with piano. Some had been one-offs, some he had arranged in concert groups of two or three; by no means all were for soprano. Ultimately, there were over 40 of them. A few have become famous: the trance-like Morgen; the spun-sugar Wiegenlied. But some of the finest - the darkly uncanny Notturno for baritone; the wild and extended Brentano setting Lied der Frauen - remain sadly little performed or recorded. Could it be that the final upwelling of orchestral song was to prove almost too successful?
Actually, Strauss's immediate reaction on completing Im Abendrot was to take one last loving trip into the past by orchestrating Ruhe, meine Seele!, a song he had composed as far back as 1894. Whether its remarkable affinity with his latest setting - the same mode of harmonic gravity, the same mood of barely achieved calm - was more a token of his expressive constancy over the decades or of his stylistic anachronism by the end, might be argued. In any case, he now turned to adding three further settings to Im Abendrot out of a volume of Hermann Hesse he had recently been given.
The first was a gently volatile setting of Fruhling (Spring) completed on 13 July. On 4 August, there followed the rapt Beim Schlafengehn (On Going to Sleep), with its Morgen-like central violin solo and ineffably radiant long-breathed climax. Last came the intricately woven September, winding down with what sounds like a final, nostalgic echo of his famous horn-playing father, and finished on the 20th of that very month, 1948. Strauss left no clear indication of any order of performance, nor did he entitle them Four Last Songs - which, indeed, strictly they were not. In November that year, he completed another short Hesse setting with piano, Malven, for the soprano Maria Jeritza, of whom he was especially fond - though this little tribute has only come to light quite recently. A short Hesse chorus was also started and abandoned before Strauss finally returned home in 1949, to receive the world's congratulations on his 85th birthday, and to die.
It was Strauss's friend Dr Ernst Roth of Boosey & Hawkes who eventually published the songs in the order Fruhling, September, Beim Schlafengehn, Im Abendrot in which they are generally heard today. And it was Britain which gained the honour of the world premiere when Kirsten Flagstad sang and Wilhelm Furtwangler conducted the Four Last Songs in the Royal Albert Hall on 22 May 1950.
And so, into a musical world in which all the advanced talk was of serialism and musique concrete and all the popular excitement centred on strenuous symphonies memorialising the last war or warning of the Bomb, there emerged a serene testament scarcely a note of which could not have been composed back in the 19th century. So why have so few performers, listeners, even critics since that glorious premiere seemed remotely worried that Strauss might have been a compromised figure or his last songs an outmoded offering? Not least of the work's virtues is to remind us that what matters is not so much the stance of the composer - whether he is deemed difficult or accessible, conservative or advanced. What matters is quality of invention, quality of feeling.
n Bernard Haitink conducts Strauss's 'Tod und Verklarung' and 'Four Last Songs' (with Charlotte Margiono, soprano) at the Proms: tomorrow 7.30pm, Royal Albert Hall, London SW7 (box-office: 0171-589 8212) and live on BBC Radio 3Reuse content