fourth, the fifth, and the octave. In making a leap to the next consonant note, the choice really lies between the third and the fourth, as the fifth is too far away. The fourth is the more audible and many nations have chosen this in preference to the third. The fourth then becomes the upward limit of the tetrachord. When it comes to creeping up or down by what may be called 'next-door' notes, the chosen interval may be one of many or quite undefined. Most commonly the major tone or the semitone were the intervals chosen, though intervals of less than a semitone were also taken in India, as we shall see from the Saman chant and from such a raga as Todi (northern).
Consonance is called Samvaditva in India. Bharata divides svaras into four kinds, and this has remained the accepted division ever since. First there is the vadi, or sounding note, or sonant. Then the samvadi, the note consonant with the vadi. Svaras between which there is an interval of nine or thirteen srutis are samvadl with each other. Svaras at an interval of two srutis from the vadi are called vivadi, or 'dissonant' in relation to it. The others are called anuvadi, or 'assonant', i.e. neutral in relation to the vadi.
The sruti or microtonal interval is a division of the semitone, but not necessarily an equal division. This division of the semitone is found also in ancient Greek music. It is an interesting fact that we find in Greek music the counterpart of many things in Indian music, and we have a good deal of information about the development of Greek music; so we may look to get help from that source in our study of Indian music. The ancient Greek scale divided the octave into twenty-four small intervals, while the traditional Indian practice is to recognize twenty-two in the octave. Rao Sahib Abraham Pandita, a south Indian musical scholar who has made a very close study of ancient Dravidian music, believes that the ancient Tamil books of the second and third century of our era support the view that in South India the octave was also divided into twenty-four equal intervals. Further investigation is being carried out in this matter, though, as has been already mentioned, a Tamil lexicon of the third or fourth
