Quintilian Institutio Oratoria 10.1.115

[115] Caelius ¹ has much natural talent and much wit, more especially when speaking for the prosecution, and deserved a wiser mind and a longer life. I have come across some critics who preferred Calvus ² to all other orators, and others again who agreed with Cicero that too severe self-criticism had robbed him of his natural vigour. But he was the possessor of a solemn, weighty and chastened style, which was also capable at times of genuine vehemence. He was an adherent of the Attic school and an untimely death deprived him of his full meed of honour, at least if we regard him as likely to have acquired fresh qualities.