I’d not previously identified much comedic potential in Mahler’s gargantuan Sixth Symphony, a piece which would feature prominently in many people’s lists of most depressing works. Which presumably explains why this astonishing concert wasn’t a sell-out, and why the prevailing gloom prompted a fair few audience members to make an intrusive dash for the exit before the double basses sounded their final pizzicato.

So we glide between seasons from one communicative diva giving her all in a vast space to another casting spells in intimate surroundings. While Joyce DiDonato, not perhaps one of the world’s great voices but certainly a great performer, was captivating the Proms multitudes on Saturday night, the Wigmore Hall’s concert year sidled in with Bryn Terfel and Simon Keenlyside, no low-key singers.

So for one last time this season the impossible colosseum of Albertopolis became the Wagnerian holiest of holies – to be precise, the Cathedral of the Holy Grail - and once again I fell in love with the beast transfigured. Justin Way, the one artist common to all seven Wagner operas as their subtle semi-stager, should be the delegate to receive the award the Proms deserve for highest achievement of bicentenary year; and it seemed right to have Sir John Tomlinson, albeit by dint of another bass’s indisposition, giving his benediction as the witness of a final miracle.

Mahler, who like most of us thought Bach was “the greatest of them all” and studied in depth the edition of his complete works, would have been delighted by last night’s extravaganza – a true celebration of what makes the Proms the much quoted “biggest music festival in the world”. Only two Bach oratorios – cantatas in all but name – could possibly follow, after a sizeable break for supper, the Mahler symphony, his Second, which ends in such a blazing resurrection.

On the one occasion I went to Bayreuth, I made the mistake of seeing The Flying Dutchman and Lohengrin after the best of Ring cycles. At the Proms we’ve had a week of serious Wagnerian withdrawal symptoms, so Tannhäuser was never going to feel like too much or too little of a good thing. In any case, this always fascinating if dramatically primitive early clash of sex and religion is shot through with later passages composed in between work on the Ring, most of them included in last night's 1875 hybrid version.

Swimming around in the Rhine is what most of us wanted to be doing on the hottest day of the year. A cooling, riverbed low E flat from Daniel Barenboim’s Berlin double basses, and then the staggered horn entries announced we were going to be in the finest sonic hands for two and a half hours  – or nearly 15, if the colossal Proms Ring is to be accounted in its full, four-night glory.

Richard Strauss’s lavish postscript to 50 years of music theatre is about so much more than the theme of its source, Salieri’s Prima la musica e poi le parole ("first the music and then the words", with a big invisible question mark). Its overall subject of rival claims in opera also embraces spoken drama, poetry, dance and specific bel canto, all of them marshalled by the most experienced of theatre directors. And a director is what this concert performance probably needed to bring its cast members into dramatic harmony.

Teamwork, as the song once said, makes the dream work. Homo sapiens knows this, if not quite by nature, then at least by nurture. Turns out that there are some chimpanzees in Leipzig which are all over the team thing too. Offered the chance to pull together on a simple mechanism to retrieve a nut – one each – two chimps will work in tandem to make it happen.

It only takes a few great Lieder by Schumann and Liszt to show the kinds of songs Wagner didn’t, or couldn’t, write. Very well, so the rarities in this programme were whimsies he composed in his youth, but even the Wesendonck Lieder, sole voice-and-piano masterpieces of his maturity, don’t show much concern for the little details of humanity. Fortunately Janice Watson rose to great form to show us what, quite apart from the two "studies" for Tristan und Isolde, their opulent generalities are all about.

With its story of youthful love entrapped by fate, Tabu relishes the glorious primal energy of the South Seas, which was where German director FW Murnau, best known now for his expressionist Nosferatu, but then recently established in Hollywood and acclaimed for the likes of Sunrise, found himself in 1929.