Here's a wacky thing. I do not really get this. Well, I do, but it's really dumb. Now, several languages are spoken here on the Iberian Peninsula, including Basque, Galician-Portuguese, Spanish, and Catalan. Some would argue that Astur-Leones and Aragones are languages, too, but I'd call them dialects of Spanish. We could fight about this forever, so let's not. Anyway, all non-prejudiced linguists agree that there is a language called Catalan which has several dialectal variants: Eastern Catalan (the generally accepted standard--on TV, for example), Rousillonese, Balearic, and Western Catalan (Lerida province and the coastal sections of Castellon and Valencia provinces). The problem is that many of those speakers in the Valencian Community prefer to think of their language as something different from Catalan. They demand official recognition of Valencian, their term for Western Catalan, as a separate language. Now, linguistically, this is completely nuts. It's all the same damn language.
Anyway, according to the Marxist interpretation of history, in the 1870s the modern Spanish state began--you know, a state with a permanent administrative bureaucracy, for which you had to qualify by passing a civil service exam. Part of the test covered standard Spanish grammar. Now, originally, you had to speak standard Spanish to get one of these primo jobs, since everybody in the bureaucracy had to communicate with one another. So some guy from Jaen could get a post in a tiny little Catalan-speaking town like Olot just by passing the Post office exam, for example.
The Catalan white-collar class, the petit bourgeois, did not like this one bit. They wanted plum civil-service jobs to stay here in Catalonia and to go to Catalans, instead of being handled by bureaucrats in Madrid or by civil servants from all over Spain working here. So they agitated for a separate Catalan civil service, for which, of course, one would have to qualify in the Catalan language. This would eliminate local postmasters or whatever from places like Jaen in Catalonia, since they wouldn't be able to pass the Catalan language test.
This is all going on at around the turn of the 20th century. The educated urban Catalan middle class wants its share of the government jobs, so it demands that certain government powers be turned over to a local Catalan administration. Those powers might be policing, education, social security, unemployment, tax collection and redistribution, labor and business regulation, the courts, etc., etc., etc. Then, not only will the locals be in charge of their own government (something that I am in favor of; I like governments that are as decentralized as possible), but they will be able to exclude outsiders from government jobs, which will now all go to the Catalan middle class.
Not coincidentally, say the Marxists, Catalan nationalism enjoyed a resurgence at around this time, which is now referred to as the Renaixenca, and most Catalan nationalists were of the middle class. This is the time in which a (rather artificial) standard Catalan was codified, in which Catalan nationalist political parties developed (la Lliga Regionalista, Esquerra Republicana, Unio Democratica), in which Catalan literature was stimulated by new interest in the language, and in which Catalan industrialists and merchants saw significant economic growth which they felt was being held back by Catalonia's being part of Spain.
Catalonia was becoming an urbanized society, and the new urbanites were nostalgic for the old ways which they left behind in the country. So they romanticized and glorified "ancient rural traditions", some of which are neither ancient nor rural. (My favorites are the adoption of pa amb tomaquet as a national food, when it was introduced in the 1910s-20s by immigrants from Murcia and southeastern Spain, and the rejection of bullfighting as something non-Catalan, which it most clearly is not; they'd been having bullfights in Catalan towns and in Barcelona for hundreds of years. Bullfighting was successfully replaced by soccer as nationalistically correct, especially by FC Barcelona, in the first decades of the 20th century.)
And, of course, there was nothing so Catalan, not even butifarra or castellers or sardanas or the Barca, as the Catalan language. So nationalist sentiment and economic pragmatism combined to make a formidable team in favor of a more autonomous, and ideally independent, Catalonia, in which the Catalan language would be mandatory. Speaking Catalan, especially the new standard Catalan, was the shibboleth.
Anyway, of course, this Catalan petit-bourgeois nationalistic movement had its response from the rest of Spain, which had its own growing urban educated middle class which did not like the idea of being shut out of government jobs in Catalonia at all. Meanwhile, the rest of Spain had its own ruralist romantic utopian illusion of Spanish tradition, and the emerging Spanish nationalism saw Catalan nationalism as its logical enemy. It was in the interests of Spanish bureaucrats to keep government powers centralized in Madrid, and to allow as little local autonomy as possible to the regions. At the same time, the Spanish middle class felt they had just as good a right to any government job in Spain, whether the job was located in Catalonia or not.
So. Back to Valencia. The Valencian region is, and was, divided between those who identify with Catalan nationalism and those who identify with Spanish nationalism. In the early twentieth century, those Valencians who sympathized with Catalan nationalism called their local language Catalan, which it is, undisputedly, from a linguistic point of view. The reaction of the Spanish nationalists--many of whom are, and were, Valencian-speaking--in Valencia was to call the local language Valencian, set up a standard Valencian grammar different from Pompeu Fabra's Catalan grammar, declare philologic independence, and demote Valencian to the level of a local patois; that is, Valencian would be considered a local artifact, and the standard language of government and education would remain Spanish. What this would do is throw Valencia in on the side of Madrid versus its eternal rival, Barcelona; bureaucracy would remain centered in Madrid, and any Spanish-speaker would qualify for a local Valencian bureaucratic job. People who spoke standard Catalan, though, and did not know standard Spanish, would not qualify in Valencia for a civil service job. This steamed the Catalans off no end, since the Valencians were locking the Catalans out of government jobs in Valencia by the same device the Catalans were using to lock the Spaniards out of their local government jobs.
We've still got these problems today. The Valencian region has generally been controlled by the Spanish nationalists among them. It is currently controlled by the Partido Popular, which has ties with Spanish nationalism. So the locals are still going off about how Valencian is not Catalan, that it's a separate language, and we speak Spanish anyway as the educated language round these parts. This bugs the living hell out of the Catalan nationalists, as they take this Valencian attitude personally. They see the Valencians as rejecting their real nationalistic purity (Catalan) for the mess of (Spanish)pottage that includes favor from Madrid. Naturally, everything Madrid (and Spain) does is an effort to screw Barcelona (and Catalonia) over, according to the Catalan nationalist perspective. And the Valencians are traitors who have sold out to Madrid and to Spanish.
Also, by the way, the standard demand by Catalan nationalist political parties is for more government powers to be transferred to the Generalitat, the regional government. Every election, both the conservative Convergence and Union and the allegedly leftist Republican Left demand more power for the Generalitat. That leads to ridiculous situations, like the duplication of unemployment offices (there's both a Catalan and a Spanish unemployment office, and as far as I know they do the same thing). And a new Catalan police force, the Mossos d'Esquadra, is replacing some of the National Police and the Civil Guard's functions, but not all of them. Or something.