  The same section of (Turing 1948) also drew the distinction between discrete and continuous machinery, illustrating the latter with ‘the telephone’ as a continuous, controlling machine. He made light of the difficulty of reducing continuous physics to the discrete model of the Turing machine, and though citing ‘the brain’ as a continuous machine, stated that it could probably be treated as if discrete. He gave no indication that physical continuity threatened the paramount role of computability. In fact, his thrust in (Turing 1947) was to promote the digital computer as more powerful than analog machines such as the differential analyser. When he discussed this comparison, he gave the following informal version of the Church-Turing thesis: