<p>The objective of this project was to develop a thematic description of a selection of documents produced during the humanistic period that includes the fifteenth to seventeenth centuries, based on a preliminary study of the letter, the result of the inputs provided by paleography in a first stage in which the reading, identification and classification of the writings were the main inputs. These documents are protected by the Orden de Predicadores in the Historical Archive of San Luís Bertrán Province, a place that preserves a prolific manuscript production and that reveals the administrative and legal horizons that were significant for the time. From these circumstances arises the fact of pointing out the general characteristics of six writing styles that allow us to understand the history of communication and part of the history of design, and thus trace those features that are maintained in the letter as it is presented to us today. This is achieved from a preliminary palaeographic approach that, while demanding arduous practice for its application, also provides a fascinating learning opportunity. For this study, legal matters were selected as a cross-sectional theme for convents and parishes. Based on a diagnosis of the object of study, an instrument is designed that temporarily locates the document, establishes the product, the series and subseries and outlines a description of the writing to define the theme. The result of the study is that the prolific scriptural manifestation responds to features of chancellor, procedural and humanistic writing mainly, although it should be noted that the qualities of execution are a determining element in the some mixed elaborations of writing with diverse characteristics.</p>