 in contrast with all and not all. Further, he studied how various forms of negation combined with quantifier expressions in (what was later called) the square of  opposition.[4]  Medieval logicians continued in Aristotle’s tradition, but also extended syllogistic reasoning to cases where A,B could themselves be quantified expressions, thus dealing with premises and conclusions like Some donkey of every man doesn’t run (example from John Buridan, 14th century). Even though Aristotelian logic falls short of the expressivity and precision of modern logic, the syllogistics certainly was a decisive contribution to the study of quantification. In fact, syllogistic systems of various expressive power have recently been studied in mathematical logic, precisely because of their affinity to natural reasoning and their simple computational properties; see  section 18  below.