Rousseau was explaining in his Essai sur l'Origine des Langues (chapter XVIII) that the musical system of Ancient Greeks has no relationship with our own system. Similarly, Lohmann asserts that it is impossible to rely on modern concepts in order to describe the Greek way of thinking. Therefore we have to relinquish concepts such as mode or scale, if we want to understand what the Greeks called “perfect system” – that is an extensive a priori of tonalities (not only lydian, mixolydian, ionian, eolian, etc., but also dorian and phrygian which are the only ones that gain Plato’s favour in the Republic).According to Lohmann, the Greek “perfect system” is an ideal construction grounded on pythagorism (in a broad sense), and it implies an essential connection between mathematics, logic, grammar and harmony (i. e. the seed of the medieval seven artes liberales), which brings to the fore the common source of logos as thoughtful language and logos as mathematical ratio – source obliterated by the modern way of thinking.