One of the apparent pillars of consistency in the medieval Latin liturgy is the divine, alias daily, office. Although scholars convincingly postulate forms of the office that both antedate the specific provisions for it which bulk large in the Rule of Benedict and reflect an urban secular (the so-called cathedral office) rather than a monastic context, in terms of actual books out of which the office was performed, not a great deal survives until roughly the eleventh century. By that time, if not before, thought is clearly being given as to how to present the contents of the office - given that much of it consists in the recitation of psalms - in a way that, while clear, minimizes repetition. This can most readily be done in the long stretch of the weeks after Pentecost and the shorter stretch (sometimes very short indeed, depending on when Easter falls) of the weeks between the octave of Epiphany and the beginning of Lent or pre-Lent (that is, from Septuagesima on). Although the structure of the office in this, to use the current phrase, ‘ordinary time’, remains the same as in the more exciting seasons of Advent, Christmastide, Lent, and Eastertide (plus, of course, the individual feasts of the Proper of Saints), the content of the various services is not driven by a particular time or saint, and so there is a somewhat abstract quality about it quite lacking from the great seasons and occasions of the liturgical year.
