BG 18.16

तत्रैवं सति कर्तारमात्मानं केवलं तु यः ।
पश्यत्यकृतबुद्धित्वान्न स पश्यति दुर्मतिः ॥१६॥

tatraivaṁ sati kartāram
ātmānaṁ kevalaṁ tu yaḥ
paśyaty akṛta-buddhitvān
na sa paśyati durmatiḥ

tatra - there; evam - thus; sati - being; kartāram - the worker; ātmānam - himself; kevalam - only; tu - but; yaḥ - anyone who; paśyati - sees; akṛta-buddhitvāt - due to unintelligence; na - never; saḥ - he; paśyati - sees; durmatiḥ - foolish.

Text

Therefore one who thinks himself the only doer, not considering the ﬁve factors, is certainly not very intelligent and cannot see things as they are.

Purport

A foolish person cannot understand that the Supersoul is sitting as a friend within and conducting his actions. Although the material causes are the place, the worker, the endeavor and the senses, the ﬁnal cause is the Supreme, the Personality of Godhead. Therefore, one should see not only the four material causes but the supreme efﬁcient cause as well. One who does not see the Supreme thinks himself to be the doer.

Bhagavad Gita As It Is.

Chapter 18: Conclusion — The Perfection of Renunciation. Text 16

Therefore one who thinks himself the only doer, not considering the ﬁve factors, is certainly not very intelligent and cannot see things as they are.