logic
... that Aristotle's system of logic formed the foundation of logical thought in the Western world for more than 2,000 years until the advent of modern symbolic logic?
... that <a href="./Aristotle" id="mwAco" rel="mw:WikiLink" title="Aristotle">Aristotle</a>'s system of <b id="mwAcs"><a href="./Logic" id="mwAcw" rel="mw:WikiLink" title="Logic">logic</a></b> formed the foundation of logical thought in the <a href="./Western_world" id="mwAc0" rel="mw:WikiLink" title="Western world">Western world</a> for more than 2,000 years until the advent of modern symbolic logic?