The Compendium of Caraka 2.2.9

2.2.9

tatra yadūrdhvabhāgaṃ tat sādhyaṃ, virecanopakramaṇīyatvādbahvauṣadhatvācca; yadadhobhāgaṃ tadyathāpyaṃ, vamanopakramaṇīyatvādalpauṣadhatvācca; yadubhayabhāgaṃ tadasādhyaṃ, vamanavirecanāyogitvādanauṣadhatvācceti//

Among these, that which takes the upward path is curable, because it can be treated by purgation and because of the abundance of medicines [available for it]; that which takes the downward path is manageable, because it can be treated by emesis and because of the scarcity of medicines; that which takes both paths is incurable, because emesis and purgation are not applicable and because no medicines can be employed.