चातुर्वर्ण्यं मया सृष्टं गुणकर्मविभागशः।
तस्य कर्तारमपि मां विद्ध्यकर्तारमव्ययम्।।4.13।।
4.13 The four castes have been created by Me through a classification of the gunas and duties. Even though I am the agent of that (act of classification), still know Me to be a non-agent and changeless.
4.13 The whole universe beginning with Brahma and ending with a cluster of grass, with the system of four stations divided according to Sattva and other Gunas and by actions like self-control corresponding to the Gunas, was created by Me. The mention of creation is for illustration. The universe is protected by Me alone and is withdrawn by Me alone. Know Me to be the creator of his manifold actions of creation etc., but at the same time to be non-agent. Sri Krsna explains here how this is possible.
Chaaturvarnyam mayaa srishtam gunakarma vibhaagashah; Tasya kartaaram api maam viddhyakartaaram avyayam.
chātuḥ-varṇyam—the four categories of occupations; mayā—by me; sṛiṣhṭam—were created; guṇa—of quality; karma—and activities; vibhāgaśhaḥ—according to divisions; tasya—of that; kartāram—the creator; api—although; mām—me; viddhi—know; akartāram—non-doer; avyayam—unchangeable