This chapter considers the Book of the Laws of the Countries, attributed to Bardaisan of Edessa (d. c. 222), as an exemplar of modes of knowing in early Syriac literature. Despite reports of a wide-ranging corpus, the only work surviving under Bardaisan’s name is this text, which innovatively combines two genres into one. The first half, a dialogue in a Platonic mode transcribed by his student Philip, considers the question of free will. Bardaisan insists that human behaviour is not determined by the stars, an argument which serves his broader commitment to divine goodness in theodicy. The second half is a catalogue, a pseudo-ethnography of peoples to the east of Edessa. The crux of the catalogue comes with a report of King Abgar VIII who ‘believed’, meaning, potentially, converted to Christianity. Regardless of confession, Abgar’s ‘belief’ serves as the culmination of both halves of this work and the ultimate proof against astral determinism. The unique and experimental work shows a foundational Syriac author wrestling with perennial questions and modes of expression at the beginning of late antiquity.