Karika 31

स्वां स्वां प्रतिपद्यन्ते परस्पराकूतहेतुकां वृत्तिम्। पुरुषार्थैव हेतुर्न केनचित्कार्यते करणम् ॥३१॥

Various causes express themselves in a mutually cooperative way to produce mental acts for the sake of the purusha only. At no point in time the instruments become the causes of acts.

Creation works for the benevolence of Purusha is reiterated by stressing the mutual cooperation of various causes and non-interference of instruments, the law of karma.