Edward Dusinberre, in his genial travelogue-cum-historical narrative, writes about this moment from two perspectives. First is the composer's: how in 1825, a convalescent in Baden two years before his death, Beethoven sketched some ideas for a completely original string quartet slow movement in one of the conversation books to which his deafness had consigned him. It was to be a Holy Song of Thanks by a Convalescent to the Deity ('a hymn giving thanks for his recovery and the reawakening of new strength', Dusinberre writes, recreating Beethoven's misplaced optimism) in which the chorale is twice interrupted by a melody of great vigour, as though the man giving thanks, keen to demonstrate signs of returned health, is too impatient to finish his prayer in one sitting.

The second perspective is that of the Takács Quartet, which in 1993 Dusinberre joined as first violinist, his studies at the Juilliard scarcely behind him. Or more accurately it is from Dusinberre's point of view, which he peppers with dialogue he has remembered or imagined, conversations in hotel foyers and rehearsal studios in different parts of the world, chains of words and ideas and sounds and disagreements and newspaper reviews and green room compliments all fighting for space and order. After a performance of Op. 132 in Normandy in 2014, the violist argues that the pulse in the chorale movement was unsteady. Dusinberre responds that if he leads too much the hymn becomes restless. The cellist counters that it will be okay if they all lead, so long as they agree on a tempo. 'Maybe you can pray in different tempi,' the violist counters, which, after all, is exactly how we sing hymns. The second violinist dislikes their tendency to slow down at key moments in the chorale – through instinct or convention he does not say – 'like an organist grinding to a halt while the church choir waits impatiently to enter', Dusinberre puts it rather well.

This one episode illustrates both the charm and the frustration of Dusinberre's book: no amount of remembered or reconstructed dialogue can come close to explaining the wondrous-strange world of a string quartet at the top of its game – what Dusinberre calls the 'underlying fragility of an enterprise that ties four people so closely to each other', a considerable advance on writer Pascal Quignard's grumpy assertion that the modern European string quartet is merely 'Four men in black, with bowties around their necks, breaking their backs over wooden bows with horsehair, over sheep entrails.'  The difficulty in capturing in prose this delicate ecosystem stems partly from the need to normalise the fragility as much as humanly possible if the quartet is to have any hope of surviving: separate flights and cars; different holiday and teaching plans; the decision whether to drink or eat together after a performance; the understanding that the privacy of the four players be respected; the paradoxical dull sense of dread shared by two quartet members if the other two become romantically involved.

Partly, though, it is because musicians do not always talk so well or revealingly about the true essence of their craft. They come across as superficial (Benjamin Britten), naughty (Thomas Adès), brilliant (Anton Rubinstein), batshit crazy (Glenn Gould), sensible (Charles Rosen): but none of these qualities, in speech or prose, indicates the sheer quality of the music subsequently composed or performed.

The current Takács Quartet (from left to right): Geraldine Walther (viola), Edward Dusinberre (first violin), András Fejér (cello), and Károly Schranz (second violin) (photograph by Keith Saunders, Flickr)

Dusinberre is better than Quignard in underlining exactly what it is that makes the enterprise of a string quartet so precarious, and he is honest on the climactic moments in the Quartet's history – Gábor Ormai's diagnosis of cancer, Roger Tapping's decision to leave the group, the selection and funding of a new set of instruments. And he occasionally buttresses the everyday fragility of their enterprise with lovely prose, with acute psychological insight: 'We had reached one of those low points that occur in a rehearsal where despite every-one's earnest desire to make progress, the relentless illumination of technical and musical challenges causes paralysis and frustration.' Yet his account mostly shies away from any real illumination of these technical and musical challenges.

Where he really succeeds is in the easy, filmic juxtaposition he manages between Beethoven climbing a craggy old mountain of his own making and the Quartet's determination, nearly two hundred years later, to follow him there. If in this narrative Dusinberre relies a little too much on Beethoven's own comment on his Op. 59 quartets – 'They are not for you, but for a later age!', which turns up throughout the book like a good and shiny penny – he can be forgiven: Beethoven's quartets were for a later age, an age that understands his cantankerous refusal to bow to the (stretched) conventions of his great teacher Haydn, or to the expectations of contemptuous musicians and audiences in whatever courtly setting Beethoven was attempting to eke out a living to match his talent, not simply the penurious existence clinging grimly to his obstinate and fractious personality. Dusinberre writes well about this aspect of Beethoven's creative life.

If we are much closer today to understanding these quartets, the late ones in particular, it is because of quartets like Takács, which for years, in performances and recordings, has kicked and pushed and skirted and honoured the boundaries of musical convention. Perhaps no more should reasonably be asked of it. In his book Dusinberre is a generous host, attempting to let in sunlight on a process and ritual usually hidden by clouds. Yet his reserved and respectful demeanour ensures that he inevitably reveals only some of the grit, courtesy, chemistry, and artistry of a modern quartet, a dance every bit as strong and courtly as that which Beethoven conjured in his Op. 132.