Bhagwad Gita
Chapter 13, Verse 4
तत्क्षेत्रं यच्च यादृक् च यद्विकारि यतश्च यत्।स च यो यत्प्रभावश्च तत्समासेन मे श्रृणु।।13.4।।
Now please hear My brief description of this field of activity and how it is constituted, what its changes are, whence it is produced, who that knower of the field of activities is, and what his influences are.