The foreigner, who is not prepossessed by any national partiality, in favour of either the Castilian or the Portuguese modifications of the Hispanic romance, might, perhaps, be induced to conclude that poetry would on the whole have sustained no essential loss, had the language of Portugal been rejected by literature, and reduced like the Galician dialect to the rank of a common popular idiom; for the Castilian poetry was from its origin, so closely allied to the Portuguese, that it is certain the former might easily have incorporated into itself the latter without producing the slightest inconsistency in any of its characteristic features. Still, however, to him who is capable of feeling the more delicate relations of the beautiful in nature and in art, it must be an increased pleasure to hear the same melody performed on two similar, yet differently constructed instruments. The historian of Portuguese literature ought, therefore, to direct his particular attention to those apparently unimportant, and yet in themselves very remarkable properties, whereby Portuguese poetry has in the varied progress of its cultivation more or less deviated from the Castilian, or, as it is now usually styled, the Spanish;[2] and also to the manner in which the differences not only of the two sister languages, but of the two nations, whose respective characters are impressed on those languages, have constantly preserved the boundary which divides the polite literature of Portugal and Spain, and which must otherwise have soon been obliterated.