Francisci Hotomani iurisconsulti observationum liber IIII

...they used to deliberate on their meaning. They possessed the responses of their predecessors, who had engaged in the same study with praise, and they had intact commentaries; and since their sects and disciplines were different, they knew which sect each one followed: whether, for instance, he had been a Sabinian, a Proculian, or a Cassian. To us, only certain scraps from those books survive, so confused, scattered, and undigested that Tribonianus seems to have inscribed these books of his Digesta Collected Laws/Digest by kat' antiphrasin by way of irony or naming the opposite. But although there are many other causes of obscurity in these books of ours, that one, beyond all others, exhausts even the most practiced scholar: it is evident that there are innumerable errors in them, which have occurred partly through the fault of time and partly through the ignorance of the copyists and scribes.