The Compendium of Caraka 1.9.10

1.9.10

kāraṇaṃ ṣoḍaśaguṇaṃ siddhau pādacatuṣṭayam /
vijñātā śāsitā yoktā pradhānaṃ bhiṣagatra tu //

The four pillars endowed with sixteen qualities are the cause of success; / but here the physician—the knower, the director, the administrator—is the primary [factor].