Bhagavad Gita Chapter 13.4
tat kṣetraḿ yac ca yādṛk ca
yad-vikāri yataś ca yat
sa ca yo yat-prabhāvaś ca
tat samāsena me śṛṇu
Translation
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.