What roman author described the technique of Opus quadratum?
Vitruvius Marcus Vitruvius Pollio (born c. 80–70 BC, died after c. 15 BC), commonly known as Vitruvius, was a Roman author, architect, civil engineer and military engineer during the 1st century BC, known for his multi-volume work entitled "De architectura". His discussion of perfect proportion in architecture and the human body, led to the famous Renaissance drawing by Da Vinci of "Vitruvian Man".
Quintus Sextius Quintus Sextius the Elder ( ; Latin: "Quinti Sextii Patris" ; fl. c. 50 BC) was a Roman philosopher, whose philosophy combined Pythagoreanism with Stoicism. His praises were frequently celebrated by Seneca.