The book is a collection of 15 studies on liturgical texts in medieval Italian manuscripts, divided into three parts, 1) 'Reading a liturgical manuscript - Roma, Bibl. Angelicus 123' (3 studies), 2) 'Orgoglio e fedeltà in Piacentinian texts' (7 studies), and 3) 'Liturgical themes in Italian manuscripts' (3 studies).
'Porta caeli' is a study of the medieval imagery and concept of Virgin Mary and the Church as 'porta caeli' in some Italian sources.