"There is no particular reason to suppose that "mental act" was intended to exclude things wider than, for example, methods of doing mental arithmetic (every now and then someone comes up with a trick for this, for instance Trachtenberg's system) or remembering things (e.g., in its day, Pelmanism)." 8. As a matter of precedent, I am free to choose between these alternatives, while acknowledging that the second comes with a clearly expressed doubt as to the correctness of the first. As a practical matter, I doubt whether the difference will normally be of concern. The views of the Court of Appeal in Aerotel make it quite clear that, like most other problems that arise with a patent, the question of patentable subject matter is essentially a question of the scope of the claim. If the claim covers a method of arriving at a particular result by the exercise of rational processes alone, then it is, in my view, a claim to a "scheme, rule or method for performing a mental act"