>> Spain’s democratic constitution of 1978, which was approved by more than 90% of Catalan voters [ . . . ] Only the Spanish parliament can change the constitution.
Not written by God, not written in stone, but also not legally allowed for Catalonia to unilaterally breach, which is exactly what the article says. Nothing more, nothing less.
The Economist article doesn't say whether Catalonia ought to be independent or not, or whether Spain was right in sending thousands of the national civil guard to disrupt the referendum, it simply says that according to Spanish law there is no ground for the referendum and therefore the Spanish government will probably not regard it as valid.
@clacke @schestowitz It is true that constitutions are not written in stone like the Tablets of the Law, and it is equaly true that boundaries are not fixed over time. But that doesn't mean that constitutions should not be respected and that nationalistic aspirations are neither iherently democratic or desirable.