It is possible to trace the origin of the word "ratio" to the Ancient Greek (logos). Early translators rendered this into Latin as ("reason"; as in the word "rational"). A more modern interpretation of Euclid's meaning is more akin to computation or reckoning.Penny Cyclopædia, p. 307 Medieval writers used the word ("proportion") to indicate ratio and ("proportionality") for the equality of ratios.Smith, p. 478
