Fr. Adrian Fortescue’s commentary on the Mass is in two parts. The first half of the book is a very detailed history of the Mass from the first century until the time the book was written in 1912. The second part is a detailed explanation of the ceremonies of the Mass in their current form (which we have today as the 1962 Missal, as changes to the Mass itself were minimal between 1912 and 1962).
When explaining the history of the Mass, Fr. Fortescue explains how Mass was said each step of the way through Church history using manuscripts and writings from that part of Church history. He explains how Mass was said in each of the rites (both eastern and western) as they developed over the first few centuries and beyond.