The music theory in the "Natyashastra", states Maurice Winternitz, centers around three themes – sound, rhythm and prosody applied to musical texts. The text asserts that the octave has 22 "srutis" or microintervals of musical tones or 1200 cents. Ancient Greek system is also very close to it, states Emmie te Nijenhuis, with the difference that each "sruti" computes to 54.5 cents, while the Greek enharmonic quartertone system computes to 55 cents. The text discusses "gramas" (scales) and "murchanas" (modes), mentioning three scales of seven modes (21 total), some Greek modes are also like them . However, the Gandhara-grama is just mentioned in "Natyashastra", while its discussion largely focuses on two scales, fourteen modes and eight four "tanas" (notes). The text also discusses which scales are best for different forms of performance arts.