prescriptive grammars and dictionaries, from the mid-20th century onwards. The relationship between standard and nonstandard varieties The phrase "dialects of Spanish" often leads to the misunderstanding that a previously uniform Spanish has split into several divergent varieties, and that nonstandard varieties are derivatives, or debasements, of standard Spanish. This is historically backwards because language has always existed in a state of variation, and standard languages are historically derived from local dialects, not the other way around. Additionally, the standardization of Spanish has led to a reduction in the amount of variation reflected in writing. In many cases, non-standard varieties, as well as Judaeo-Spanish, retain features which were once common in written, standard Spanish. For instance, while there was variation in the imperfect and conditional endings of verbs between the now-standard , and and (ie 'I had, I would sing') in writing up until the end of the fourteenth century, the variant could still be heard in rural areas of the Province of Toledo as of the later 20th century. Likewise, until shortly after the end of the fifteenth century, words that had inherited syllable-final v alternated with forms in which that v had been vocalized to u. While forms with u, such as 'debt' and 'city' are now standard, Judaeo-Spanish prefers forms with the original v. The preterite forms of some irregular verbs had multiple variants until the 17th century. Thus, the verb 'to bring' could be conjugated 'I brought, he brought', alongside modern (now spelled with and not ). The variants are still found in some predominantly rural nonstandard varieties. Although a has been added to the stems of many verbs' first-person singular present indicative and present subjunctive forms, such as from earlier , some other forms such as , common in literary Spanish until the 17th century, are now restricted to nonstandard speech. Until the mid-16th century, the short subject forms 'we, you' were still found alongside the expanded forms in writing. The shorter form is used in Judaeo-Spanish, alongside the expanded , and the use of non-deferential, singular continues in much of Latin America, where it has become known as . While has become part of standard usage in some countries, such as Argentina, its existence has always been controversial, and it remains stigmatized in other locations. Standard Spanish may be seen as a type of roof covering and influencing the various spoken dialects of Spanish. Individual