Karika 33

अन्तःकरणं त्रिविधं दशधा बाह्यं त्रयस्य विषयाख्यम्। साम्प्रतकालं बाह्यं त्रिकालमाभ्यन्तरं करणम् ॥३३॥

Internal instruments are of three kinds, and external instruments are tenfold reflecting the topics of the three. External instruments operate only at present time. Internal instruments operate at all three times.

Internal instruments are the mind, the ego and the intellect. External instruments are 5 sense organs and 5 organs of action. External instruments always reflect the collective outcome of mind, ego and intellect. Critical distinction is made between them in terms of time of their operation. Internal instruments operate at all three times, past, present, and future with the help of memory and imagination. External instruments can operate only in the present.