Sulpicius Cornelianus was a Roman

Ancient Rome

Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....

 rhetorician. He lived in the reign of the Roman Emperor

Roman Emperor

The Roman emperor was the ruler of the Roman State during the imperial period . The Romans had no single term for the office although at any given time, a given title was associated with the emperor...

s Marcus Aurelius and Verus

Verus

Verus may refer to:* Verus , Roman centurion and senator* Verus , Roman gladiator-See also:* Lucius Verus , Roman co-emperor with Marcus Aurelius* Gnaeus Julius Verus , Roman general and senator...

. This puts him in the late 2nd century (Aurelius and Verus reigned from 161 to 180). Cornelianus acted as secretary to Marcus Aurelius.

The grammarian Phrynichus Arabius

Phrynichus Arabius

Phrynichus Arabius or Phrynichus of Bithynia was a Greek grammarian who flourished in 2nd century Bithynia, writing works on proper Attic usage...

 speaks of Cornelianus with high praise; Phrynichus dedicated his Ecloga to him, and describes him as worthy of the age of the great orator Demosthenes

Demosthenes

Demosthenes was a prominent Greek statesman and orator of ancient Athens. His orations constitute a significant expression of contemporary Athenian intellectual prowess and provide an insight into the politics and culture of ancient Greece during the 4th century BC. Demosthenes learned rhetoric by...

.

Fronto is our source for the fact that Cornelianus was named Sulpicius.

It has been argued that Cornelianus is the author of a surviving treatise in Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 entitled Philetaerus , which had previously been attributed to the great 3rd century grammarian Herodian

Aelius Herodianus

Aelius Herodianus or Herodian was one of the most celebrated grammarians of Greco-Roman antiquity. He is usually known as Herodian except when there is a danger of confusion with the historian also named Herodian....

. Herodian, too, was on good terms with Marcus Aurelius.