The Latin was the spoken and literary language of the Romans till the first Century BC. At that time the quick expansion made it necessary to change the official language to bilingual (Latin and Greek) which in turn means that the Latin survived only as Literary Language (Catullus, Ovidius, Cicecro, Horace, Virgil, Propertius, Plyny the younger, Tacitus and so on), and the Latin as sopekn language revived only through the 4th Century, when the Eastern and Western Empires were divided. From that time till the end of the first millennium the Latin was spoken and written language of the Western Christianity.
The Mass originaly was multilingual (Greek, Coptic, Syrian etc), Latin was not among the languages of the Mass, because only an elite spoke it. At the End of the 4th century AD pope Damasus decided to translate the scriptures to Latin (from Greek and Hebrew) and ordered it as the official language for the Mass for the Western World. The Eastern churches kept their multilingual nature, and in the 9th Century when the Slavic tribes were converted the Slavic became also official language of the Mass.
In the West until the 14th Century the Latin was the only written language in the majority of the Western world. It was first the English which felt the necessity of the vernacular, and John Wycliffe translated the Bible Almost certainly his translation was used in the Mass, the Church wanted the active participation.
In the 15th century the liturgy suffered the same crisis like today. The technology of the printed books provided the means, and everybody believed that they can make better worship than the traditional. The reformators entirely changed to vernacular and in response Rome restricted the language of the Liturgy to the Latin.
As a result England, Germany, Scandinavia, the half of Western Europe was lost to the Catholic Church. The Catholic Church remained only in the countries which spoke the romance languages (Spain, France, Italy and under their influences; and also for political reasons in Austria and the countries under her influence: Hungary and partly Poland) In this countries the vernacular hymns helped to survive the Catholic Latin mass and through that the Catholic religion. *.
As the spoken languages even in the romance countries distanced from the Latin, the Mass lost the connection with the people. People were required only present. St Pius X felt that it is wrong and pushed the active participation. The consequence is the confusion today. We hope that is is temporary, but certainly the language will accommodate to the people. The Mass as a rite, words if not final value, it is for the people, and not the people for the mass.*