σύγκρισις or comparison

σύγκρισις is the 10th of the ancient progymnasmata and is the exercise in comparison.  Theon writes:

"Syncrisis is the language setting the better or worse side by side.  There are syncrises both of persons and things." (Theon, 112, Kennedy).

As with the exercises of encomium and invective, the topic lists derived from those exercises are also used for syncrisis.  For example,  there are external goods such as place of birth, occurrences at birth, nurture, upbringing, education. Goods of the body (health, strength, etc.).  Then there are internal goods such as goods of the mind (intellect, wisdom), virtues (justice, bravery).  Then there are actions and deeds (to which I would also add speech).  Finally, there is the manner of death and what happened after death. Whereas with encomium and invective, the student merely listed the goods or ills of a single person or thing.  With syncrisis, the student compares two subjects with regard to these topics.

Syncrisis can take many forms, comparing good with good (double encomium), good with bad (encomium/invective), and bad with bad (double invective).  One can also come to a number of conclusions.  For example, with a double encomium, one could find the two equally good, or might praise both, but find one slightly better.  Likewise, with a double invective, one might find the subjects equally bad, or that one is slightly more diabolical than the other.

I have dealt elsewhere with syncrisis in the Stephen episode in Acts 6-8.  Another example of syncrisis can be found in the book of Hebrews.  In chapter 3, the author of Hebrews compares Jesus to Moses as follows:

Heb. 3:3 Yet Jesus is worthy of more glory than Moses, just as the builder of a house has more honor than the house itself.
Heb. 3:4 (For every house is built by someone, but the builder of all things is God.)
Heb. 3:5 Now Moses was faithful in all God’s house as a servant, to testify to the things that would be spoken later.
Heb. 3:6 Christ, however, was faithful over God’s house as a son, and we are his house if we hold firm the confidence and the pride that belong to hope. 

Here, the author of Hebrews engages in a syncrisis between these two biblical figures, Jesus and Moses.  The comparison is a double encomium in that Moses is not found to be bad.  No, indeed, Moses was a faithful servant over God's house.  Yet, even though Moses is good, Jesus is better, not as a "servant" over God's house, but as a "Son."  Thus, the author of Hebrews has composed a double encomium syncrisis finding both subjects laudable, but finding Jesus superior as a Son.