The New Liturgical Movement has a post with a translation from the Rationale Diviniorum Officiorum by the thirteenth century jurist and commentator Guillaume Durand ( Durandus ) Bishop of Mende. Born c.1230 in southern France he spent virtually all his career in Papal service in Italy. He died and was buried in Rome in 1296. There is an account of him and his writings at Guillaume Durand
The NLM post can be seen at Durandus on the Liturgical Customs of Lent
Rather than his legal text the Speculum Iudiciale the Rationale is probably today the best known of his works, being often used by historians of the liturgy for its account of practice in the author’s lifetime and for its insights into medieval interpretations of ceremonial and of the use in that context of Biblical and other sources. In particular his discussion in Book One of his work of the symbolism involved in the design of a medieval church has a particular fascination and helps one understand what we can still see today and what was in the mind - or what Durandus thought was in the mind - of the medieval builders. First printed in 1459 it has retained a continuous readership and had wide influence.
For those of you interested further in this absorbing insight into liturgical history and practice I see that Amazon offers editions of the various parts of the sizeable work on their website. So if you are still looking for Lenten reading, and have the spare cash, then Durandus can be delivered to your door.