For the most part, we live our lives in a world of calculation, estimation and approximation. The vast amount of data that we possess or acquire and are expected to process, the number of decisions we make and the quantity of law which, whether we know it or not, affect our every move, make us as dependent on our intuition as on our intellects. In our everyday private lives, we understand and accept that this is so. That is why we do not travel precisely within the speed limits laid down for us, do not make exact calculations as to whether and when we can pay for each item purchased on a credit card, and do not take legal advice before shaking a stranger’s hand or kissing a proffered cheek as to what level of response might incur civil liability. In short, if our conduct generally falls within a fuzzy and ill-defined category of normality, we forget about it and concentrate our attention on more important things. The great divide between common law and civil law traditions is instructive because it suggests that, in legislative terms, those who live within the civilian culture are comfortable to be guided by general principles, to which they adhere unless and until new principles, legislatively enacted or judicially articulated, nudge them into a different direction. The common law tradition, which is perhaps more focused on the precise meanings of words than on their general drift, has however produced two great English-speaking nations populated by those who, while, abjuring the literal interpretation of statutes and precedents, are magnetically attracted to literalism and cannot literally get it out of their system. This divide is found in intellectual property law where, in the United States, each word of a legislative draft becomes a battleground over which battles economic, political, cultural and semantic are fought, the contestants each invoking the terms of a constitution which are expressed in terms of principle which warmly accommodate a variety of conflicting positions. It is also found in the European Union, where the relatively spare and principled prose of harmonising directives, nourished by the fertile pronouncements of their respective recitations, is accommodated in the national law of civil jurisdictions with greater ease and at less length than in common law lands, where the notion that Parliament means what it says —and means to be silent over that which it does not say —remains deep-rooted. Copyright and patent law both furnish food for thought in this context. In the United States, in Canada and in the United Kingdom there has been continued tension as to the correct dividing line between copyright infringement and the fair use by one person of another person’s copyright-protected work. This has generated proposals for legislative reform, legal and economic reviews, litigation and furious lobbying. In similar vein neither the passage of the America Invents Act, nor the declaration that an acceptable solution has been found for the one-Europeone-patent question, has led to debate dying down. Rather, it has shifted it from one set of issues to another.