The quote is in line with a lot of reflections by liberal aristocrats or clergy in the sphere of liberal aristocrats (broadly, what we might call the 'liberal high society' of early-Revolutionary Paris - think Germaine de Staël's salon, or the 'revolutionary' fêtes attended by Thérésia de Fontenay). Essentially, during the early phase of the Revolution, before the escalation of popular and political violence that happened over the course of 1792, the liberal aristocracy were in their golden period. Their ideas for the reform of France were being discussed, reworked, and put into action by the National Assembly, and politics was as much a social activity as parties were.

Grand fêtes, both official and private, were held, with the private ones exchanging meticulous etiquette and careful dress for free-thinking, muslin gowns, and picnics in grassy meadows, in touch with nature and innocence in the finest traditions of Rousseauian thought. Freed from the need to wait on court and observe the strict social season, these nobles threw as many entertainments as they could. These 'revolutionary' parties were of course as much an affectation as the ancien régime balls had been, but they were new and seemed far less hypocritical than royal parties had been. Change was in the air, change that particular class of aristocrats had been working towards, agitating for, and talking about for years, if not decades, and life seemed, for many of them, full of boundless possibility.

The marquis to Frénilly wrote later that Paris "Had never been so brilliant. One might have thought that people were accumulating joy to last them all the time they were about to sorrow... There was something prophetic in this surfeit of pleasures. We had the art of amusing ourselves out of foresight, like people who lay in a supply of food against famine."

That quote gets to the other, darker side of the Talleyrand quote. As popular and political violence became more and more extreme - and with that came the radicalisation of the government - France began to slide towards the Terror, especially after the declarations of war in 1792 and the proclamation of the Republic. The liberal nobility were soon in very real danger for their lives, and the kind of extravagances they had indulged in would now mark them as guilty of incivisme and land them a date with Madame Guillotine. Many of these liberal nobles followed their more reactionary colleagues and became émigrés during this period, and only returned to France during the Consulate and Empire.

Both Talleyrand and Frénilly are writing from hindsight. Few liberal nobles expected the radicalisation of France and the Terror, but in hindsight, after those events, the years around 1789 - years of limitless possibility, of a constitutional monarch, of France renewed and unified as one nation, its wounds healed, of revolutionary parties and free expressions of emotion and sensibilities without the shadow of the guillotine or of endless war - seemed like a golden age, one whose sweetness was heightened in hindsight by the shadows of the Terror and the wars that followed.

Sources:

Liberty: The Lives and Times of Six Women in the French Revolution, by Lucy Moore

The Oxford History of the French Revolution, by William Doyle

Tallyrand was born into a life of privilege, if not perhaps of wealth. Both his parents being younger children of the nobility, they didn't inherit any estates, and his father was an officer in the army, However, both had connections at court, and plenty of Tallyrand's relatives were wealthy and well connected. According to his own memoirs, after having a rather miserable time of it at school and being forced to take up a career in the church, Tallyrand then turned to using his connections to put himself in a position to become a successful politician. Basically, he spent most of his time prior to the Revolution swanning around Paris, befriending the leading intellectuals and beautiful women of his day, having excellent dinners and engaging debates at various salons around Paris. Nice work if you can get it, especially for Tallyrand, who was known as a gourmand and lover of luxury his whole life.

But it's a little more complicated than that. Tallyrand was a child of the Enlightenment, and recognized the need for reform of many of the institutions of the Ancien Regime. However, he was also a son of the nobility, and could be rather sentimental about the relationship between the aristocracy and the peasants prior to the Revolution. Some of the only happy times of his childhood were spent at his great grandmother's provincial estate. In his memoirs, after describing a ritual his great grandmother conducted after Mass every Sunday in which local people could visit the apothecary at her chateau to be treated for any ailments they might have -- she apparently attended herself and trimmed the bandages --- he says:

"If I displayed affectionate and even tender feelings without too much familiarity, if, in various circumstances, I showed pride without haughtiness, if I love and respect old people, it is at Chalais, by the side of my grandmother, that I imbibed all the good feelings which surrounded my relatives in that district, and which they enjoyed with delight. For, there are feelings which increase from generation to generation. For a long time to come, people, whose fame or fortune are of recent origin, will be unable to appreciate their sweetness."

There's that word again, sweetness. For Tallyrand here, that particular sweetness of life can only emerge from a stable society in which every person knows their place and works to maintain that stability and peace. That attitude is linked with his work as a diplomat --- despite all his side-swtiching, throughout his political career Tallyrand tried to engineer a stable peace for France, which meant creating a stable balance of powers across the continent.

I did find that the quote is from Memoires pour servir a l'histoire de mon temps par M. Guizot, page 6, where it says,

Ce n'est pas que je fusse, a cette epoque, tres-preoccupe de la politique, ni tres-impatient que la liberte m'en ouvrit l'acces. Je vivais dans la societe de l'opposition, mais d'une opposition qui ne ressemblait guere a celle que nous avons vue et faite pendant trente ans. C'etaient les debris du monde phisophique et de l'aristocratie liberale du XVIII siecle, les derniers representants de ces salons qui avaient librement pense a tout, parle de tout, mis tout en question, tout espere et tout promis, par mouvement et plaisir d'esprit plutot que par aucun dessein d'interet et d'ambition. Les me-comptes et les desastres de la Revolution n'avaient point fait abjurer aux survivants de cette brillante generation leurs idees et leurs desirs; ils restaient sincerement liberaux, mais sans pretentions pressantes, et avec la reserve de gens qui ont peu reussi et beaucoup souffert dans leurs tentatives de reforme et de gouverment.

Ils tenaient a la liberte de la pensee et de la parole, mais n'aspiraient point a la puissance; ils detestaient et critiquaient vivement le despotisme, mais sans rien faire pour le reprimer ou le renverser. C'etait une opposition de spectateurs ou le renverser. C'etait une opposition de spectateurs eclaires et independants qui n'avaient aucune chance ni aucune envie d'intervenir comme acteurs.

Societe charmante, dont, apres une longue vie de rudes combats, je me plais a retrouver les souvenirs. M. de Talleyrand me disait un jour: "Qui n'a pas vecu dans les annees voisines de 1789 ne sait pas ce que c'est que le plaisir de vivre." Quel puissant plaisir en effet que celui d'un grand mouvement intellectuel et social qui, loin de suspendre et de troubler a cette epoque la vie mondaine, l'animait et l'ennoblissait en melant de serieuses preoccupations a ses frivoles passe-temps, qui n'imposait encore aux hommes aucune souffrance, aucun sacrifice, et leur ouvrait pourtant les plus brilliantes perspectives!

And my humble attempt at a translation:

It was not that I, at the time, was very pre-occupied with politics, nor what I was very eager for liberty. I was living in the society of the opposition, but one that hardly resembles that which we have seen in these thirty years. What the damage upon the world of philosophy and the liberal aristocracy of the 18th century, the last representatives of those who thought everything for liberty, talks about everything, questions everything, and all hoping for the promise of the movement yet did not themselves have ambitious purpose. The personal accounts in the disasters of the Revolution has not abjured the survivors of this brilliant generation due their ideas and desires; they remained sincerely liberal, but without pressing pretentions, and with the reservation of the people who have succeeded and suffered a little in their attempts at reform and government.

They wanted freedom of thought and speech, but never aspired to power. They hated and were highly critical of despotism, but without doing anything to suppress nor reverse it. It was an opposition made up of spectators, or worse. It was an enlightened opposition of independent spectators who had no chance nor desire to intervene as actors.

The charm society, which, after a long life of hard battles, I like to find its relics. Talleyrand once said to me, Who has not lived in the neighboring year 1789 does not know what it is that the pleasure of living. What a powerful pleasure indeed, that of a great intellectual and social movement, far from dead at this worldly time, yet animated and ennobled in the serious concerns of this frivolous hobby, which still required the men no suffering, no sacrifice, yet made available their most brilliant prospects!

So, those of you who actually speak French please correct me on the above terribad translation. But if I understand the context as relayed by M. Guizot, that quote of Talleyrand spoke to the "lost generation" of liberal intellectuals.