 Bartók had realised that both melodic minor scales gave rise to four chromatic steps between the two scales' fifths and the rising melodic minor scale's seventh degrees when superimposed.Consequently, he started investigating if the same pattern could be established in some way in the beginning of any scales and came to realise that superimposing a Phrygian and a Lydian scale with the same tonic resulted in what looked like a chromatic scale.Bartók's twelve-tone Phrygian/Lydian polymode, however, differed from the chromatic scale as used by, for example, late-Romantic composers like Richard Strauss and Richard Wagner.