Parts and themes of the Corpus could be listed as follows:
Digesta: It collected all of the classical jurist’s writings on law and justice;
The Code (Codex). It outlined the actual laws of the empire;

The Institutes (Institutiones). It summarised the Digest and intended as a textbook for students of law;
A fourth part, the Novella (Novellae) was made later to update the Code with new laws of Justinian.