  There is, however, one telling point of contact between Aristotle’s investigations into the soul and the contemporary discipline of Psychology: in each case, different questions yield different directions and methods of inquiry, with the result that it is sometimes hard to appreciate how so many variegated enterprises, though conducted under one and the same rubric, could really belong to any one coordinated discipline. Someone studying methods of Freudian psychoanalysis will not, after all, have any immediate overlap of either interest or method with a brain physiologist or a behavioral geneticist. In a similar way, Aristotle seems reluctant to regard an inquiry into the soul as belonging exclusively to natural science, which is for him the branch of theoretical science devoted to investigating beings capable of undergoing change. (He contrasts “physics”, that is, natural science, with both mathematics and “first philosophy” along these lines; Meta. vi 1 1025b27–30, 1026a18; xi 7 1064a16–19, b1–3.) On the one hand, he insists that because various psychological states, including anger, joy, courage, pity, loving, and hating, all involve the body in central and obvious ways, the study of soul “is already in the province of the natural scientist” (De Anima i 1 403a16–28). At the same time, however, he insists that the mind or intellect (nous) may not be enmeshed in the body in the same way as these sorts of states, and so denies that the study of soul falls in its entirety to the natural scientist (Meta. vi 1 1026a4–6; De Partibus Animalium i 1 645a33-b10). This is presumably why in the opening chapter of De Anima Aristotle reports a deep and authentic perplexity about the best method for investigating psychological matters (De Anima i 1 402a16–22). If different sciences employ different methods and the study of soul is bifurcated so that it belongs to no one science, there will indeed be a genuine difficulty about how best to proceed in any inquiry concerning it. It seems fair to say that these sorts of quandaries have not left us altogether. Although purely naturalistic approaches to philosophy of mind have found staunch champions in contemporary times, it would nevertheless be safe to say that much of the discipline continues to employ traditional a priori methods; some branches of cognitive science seem an admixture of both. In any case, in view of the difficulties concerning the soul he enumerates, Aristotle evinces an appropriate modesty when undertaking its investigation: “Grasping anything trustworthy concerning the soul is completely and in every way among the most difficult of affairs” (De Anima i 1 402a10–11).