My main purpose … has been for Your Majesty to see … how wrong is what many have tried to persuade you of, that these indigenous peoples of the Kingdom of Peru are barbarians …, which you will clearly recognize when you see this grammar, the great organization this language has, the abundance of words, the convenience they have in the things they mean; the different and curious ways of speaking; the soft and good sound of its pronunciation to the ear, the easiness to write it with our letters; how sweet and easy is the pronunciation compared to our language; its being properly organized … in terms of declension and the other characteristics of the noun, the tenses, and the persons of the verb; thus a language, Your Majesty, so polished and abundant, regulated and enclosed in the rules and prescriptions of Latin such as this (as is shown through this grammar), not barbarian, … rather it can be called very polished and delicate … Santo Tomás  1951 Grammatica, p. 9-10, transl. SDS).
Considering that descriptive linguistics in general and the description of languages other than Latin and Greek in particular had only just started to develop in Europe, the missionaries’ achievement was pioneering. We are only now starting to investigate the effects these descriptions had on languages in the context of colonisation and Christianisation (i.e. how far did the description based on an Indo-European angle influence the development and usage of the languages themselves) and on general linguistic description.
The colonial missionary-grammarians wrote gramáticas or artes, which were guides to ‘the art of speaking and writing well’. These grammars were often accompanied, either in the form of a separate book or as part of the work, by dictionaries or vocabularies which explained the Amerindian words in Spanish; these were often called vocabulario but sometimes lexicón or phrasis.
For those who study Andean cultures and languages, these colonial linguistic works are of interest in various respects. On the one hand, they provide linguistics scholars with early data about the structure of otherwise unwritten languages at all linguistic levels (phonology by means of pronunciation and orthography, semantics through the lexicon, grammar through morphology and syntax). On the other hand, the comprehensive dictionaries and the more or less detailed vocabularies which accompany the grammars are inventories of many aspects of material and non-material culture. Most of these works also include Christian doctrinal texts, which, compared with each other and examined as to changes in the vocabulary, can be of interest to historians, theologians, and historical linguists. In the realm of material culture there are many terms which reflect indigenous usage (for example in agriculture, herding, or textiles). In the spiritual sphere, however, apart from terms referring to Andean belief forms and practices (e.g. ‘sacrifice’), numerous words or meanings were newly created for missionary purposes (e.g. the same term ‘sacrifice,’ but with a Christian meaning). For this the authors used different strategies: transference of the indigenous meaning to the new European meaning and creation of new words, composed either of Amerindian forms or forming new hybrid words and phrases. Especially in the religious domain – but also in the other spheres – we have to be careful when using the terms provided by the Christian priests because it cannot be determined whether they understood correctly what they were told and they may have voluntarily or involuntarily distorted the original meanings.
A short biography of the authors of these works, followed by a review of the editions of each study with information on its availability, its contents, its linguistic characteristics and its potential for use in Andean studies can be found in Dedenbach-Salazar Sáenz 2008 Dictionaries (on grammatical aspects of missionary Quechua see Dedenbach-Salazar Sáenz 1997 La descripción gramatical).