When studying history, at some point you have to stop looking at the trees and take in the entire forest. The 19th century is so important and complex that the death of Philidor is the appropriate place to mark as a vantage point for looking behind from where we've been and ahead to where we're going.
Some people may think that recounting ancient chess manuscripts, books and authors is somewhat boring, but the fact remains that these books, along with some indirect references, are our only glimpses into the past and it's only by studying these things and making rational assessments that we can understand anything about the past. So we know approximate dates of some, exact dates of others, we know the language they were written in and often some things about the authors.
Then all these things must be interpreted and extrapolated. So, we feel, thanks to Lucena and others, that modern chess began around the end of the 15th century and that in some places, particularly in parts of Spain, most of the present day rules already existed. But chess was being played in other places too. Chess was played in such places as Scandinavia, Holland, Germany and Russia, but in an earlier form. These countries were much slower to adapt to the modern rules. Italy caught on fast, probably partly due to the fact that areas of it, along with Spain, fell under the Hapsburg rule but also because of the Renaissance which was in full force in Italy.
Italy was not a united country and during the Renaissance city-states gained strength and influence under the rule of powerful families and many of these families, such as the Medicis, supported the arts and, thankfully, chess. While Spain had it Valencian chess cliques and the court of Phillip II with the world's leading player and writer, Ruy Lopez, the priest from Zafria, Italy produced even better players such as Paolo Boi and Leonardo di Bono. Thanks to them and their popularity in part, some more manuscripts were made and some more books were printed. They greatly influenced both Salvio and Carrera.
One thing that should be kept in mind is that books weren't printed as they are today. Printing was an expensive, time-consuming process and books weren't at all cheap. Almost no one printed on speculation and orders, or subscriptions, were taken prior to making a run and these runs were generally pretty small. So, books weren't lying around, but rather carefully encased in libraries of the wealthy.
Up until the Renaissance, chess was indeed the Game of Kings - of kings and of the clergy, that is. One reason for this was the availability and the perception of recreational time. Peasants generally didn't have a lot of free time to spend playing time-consuming games, and, in fact, the church discouraged this type of recreation - for the peasants. In the courts and monasteries chess was rationalized away as a mental exercise rather than a game. But the Renaissance helped change the ways people looked at things. Humanism and individuality were the hallmark of that period, but so was the rise of the middle class. Merchants, bankers, artisans all came into demand and many became nouveau riche. So, with free time and plenty of money, people other than aristocracy and clergy could afford books and the time to read them and to play games. Chess started moving from the courts and monasteries to the merely wealthy. This was an important step in itself.
But chess didn't have the social or political place at this time as, for instance, it had in 20th century Russia, and it's popularity ebbed and flowed as circumstances changed. Spain, more or less, dropped out the chess picture, and, except for Greco and his manuscripts of traps, not a lot was heard out of Italy, or anywhere else for that matter, for the next 100 years. But, apparently chess was being played, though few books were written and no games recorded, because in the middle of the 18th century we see Lolli, Ponziani and del Rio (of the Modenese school) in Italy and Philidor and the players at the Café de la Régence in France. They didn't materialize out of nowhere. Philidor's life and chess is fairly well documented. We also know chess was being played at the Café de la Régence and the Procope coffehouses before Philidor's time. In that sense, chess was flourishing, though in an informal and limited way, in Paris more so than in other places. When these coffeehouses became meeting places for the intelligentia, chess gained a little prestige too.
Then came Philidor.
Philidor not only helped change they way chess was played, but also the way chess was taught and studied. Equally important, Philidor, "The greatest chess-player amongst musicians and the greatest composer amongst chess-players," played in both Paris and London. His popularity and connections in England helped spark the English chess movement in ways the wouldn't be felt until 40 years after his death.
But the immediate post-Philidor period was one of deceptive quiet. The French Revolution squelched chess in Paris for a few years in spite of the fact that Robespierre, the architect of the revolution, was a chess player and frequent visitor of the Café de la Régence. It gradually resurged, housing such champions as Deschapelles, la Bourdonnais and Saint-Amant. In London coffehouse and chess clubs came and went. Verdoni replaced Philidor as house player at Parsloe's (which closed down around 1825) and Sarratt became the professional at the Salopian coffehouse about the same time. But no one, other than Maezel's Turk, had the draw that Philidor had. Chess lost some of it's fair-weather supporters who felt it was now out of fashion and so the game had rather limited visibility. But beneath the surface was the faint rumbling of a volcano waiting to explode.