Likewise, combination of three rasas together result in twenty substances. There are fifteen combinations of four rasas together. They are formed as follows: The group of sweet and sour tastes, combines with any two of remaining tastes beginning with salt in six different ways. They this form the ‘group of fours’ of tastes.
त्रिरसानि यथासङ्ख्यं द्रव्याण्युक्तानि विंशतिः| वक्ष्यन्ते तु चतुष्केण द्रव्याणि दश पञ्च च ||१७||
Thereafter, the group of two-sweet and salt combining consecutively with pungent, bitter and astringent, form with the addition of sour, astringent and pungent respectively, three separate ‘group of fours’.
Thereafter the group of twos of sweet and pungent combining with residuary group of two of bitter and astringent tastes, forms ‘group of fours’. Thus with the sweet taste as a constant factor, there are ten distinct groups ‘four tastes’.
Now, dropping the sweet taste, the group of two of sour and salt combining consecutively with pungent, sour and astringent tastes forms with the addition respectively of bitter, astringent and pungent tastes, three separate groups of ‘four tastes’. (1) sour-salt-pungent-bitter (2) sour-salt-bitter-astringent (3) sour-salt-astringent-pungent.
कट्वाद्यैरम्ललवणौ संयुक्तौ सहितौ पृथक्| यातः शेषैः पृथग्योगं शेषैरम्लकटू तथा ||२०||
Now, dropping the salt taste, the group of two of sour and salt combine with the residuary two groups of bitter and astringent to form one fresh group of four tastes.