  Very little is known about the development of logic from c. 100 BCE to c. 250 CE. It is unclear when Peripatetics and Stoics began taking notice of each others’ logical achievements. At some point during that period, the terminological distinction between ‘categorical syllogisms’, used for Aristotelian syllogisms, and ‘hypothetical syllogisms’, used not only for those introduced by Theophrastus and Eudemus, but also for the Stoic propositional-logical syllogisms, gained a foothold. In the first century BCE, the Peripatetics Ariston of Alexandria and Boethus of Sidon wrote about syllogistic. Ariston is said to have introduced the so-called ‘subaltern’ syllogisms (Barbari, Celaront, Cesaro, Camestrop and Camenop) into Aristotelian syllogistic (Apuleius Int. 213.5–10), i.e. the syllogisms one gains by applying the subalternation rules (that were acknowledged by Aristotle in his Topics)