ABSTRACT
Members of Christian communities developed a keen sense of the role played by the written word in preserving and fostering orthodox tradition handed down by the Church, and in transmitting that heritage to new generations. Their appreciation of the importance of this role generated a new attitude to the written word, which promoted it to the position of a medium in its own right, whose function was no longer seen to be wholly dependent upon the spoken word. One of the earliest witnesses to this change of attitude is Isidore of Seville. A scribe had no immediate respondent to interact with, therefore he had to observe a kind of decorum in his copy in order to ensure that the message of the text was easily understood. This decorum - the rules governing the relationships between this complex of graphic conventions and the message of a text conveyed in the written medium - may be described as 'the grammar of legibility'.
