  The pressing issue concerning philosophy, faith, and theology in the 1250s was how to set up theology as an Aristotelian demonstrative science. Albert had done so in his commentary on the Sentences (1243–9), which Bonaventure had on hand when writing his own commentary. Demonstration is causal knowledge, and a science in Aristotle’s sense is systematic knowledge of one limited subject developed through demonstrating necessary conclusions by making use of certain fundamental causal principles relevant to the subject at hand.  The task theology had set itself, then, was to discover and present systematically the truths set out in that most unsystematic of books—the Bible.