[272] So Theodoros in the Theaitetos.
[273] Xen. Econ. viii. 14.
[274] Xen. Mem. iv. 4. 7.
[275] Aristoph. Wasps, 656.
[276] In Diogenes Laertius, i. 2. 10.
[277] Alexis (in Athen. 117 e).
[278] An abacus of a very similar sort is still in use in China and Japan, even in banks. The “pebbles” are pushed to and fro, not in grooves, but on wires passing through the middle of them. Calculations can be made by this means with marvellous rapidity.
[279] e.g. Polit. 299 D. πεττείαν ἢ ξύμπασαν ἀριθμητικήν.
[280] Plato, Phaid. 274.
[281] Plato, Laws, 819 B.