तत्क्षेत्रं यच्च यादृक्च यद्विकारि यतश्च यत् | स च यो यत्प्रभावश्च तत्समासेन मे शृणु || ४ ||
tat kṣetraṁ yac ca yādṛk ca yad-vikāri yataś ca yat sa ca yo yat-prabhāvaś ca tat samāsena me śṛṇu
tat—that; kṣetram—field; yat—what; ca—also; yādṛk—as it is; ca—also; yat-vikāri—with what modifications; yataḥ—wherefrom; ca—also; yat—what; saḥ—he; ca—also; yaḥ—who; yat-prabhāvaḥ—what influence; ca—also; tat—that; samāsena—in summary; me—from Me; śṛṇu—hear.
“Hear briefly from Me what the Field is, what its nature is, what its modifications are, whence it comes, who the Knower of the Field is, and what His power is.”
Krishna promises a systematic teaching covering six aspects: the nature of the Field, its qualities, its modifications (vikara), its origin, the identity of the Knower, and the Knower's powers. This is a complete epistemological and metaphysical curriculum compressed into one chapter. The sage who masters these six aspects is established in right understanding of both the phenomenal world and transcendent Reality.
Approaching spiritual teachings with the question 'what is this field of experience made of?' is itself a contemplative practice. Notice the components of your inner field: sensations, emotions, thoughts, memories, desires. See how they arise and pass. That which notices them — undisturbed, unmodified — is the Knower.