Śvetāśvatara Upaniṣad · 1..3
रूपं रूपं प्रतिरूपो बभूव तदस्य रूपं प्रतिचक्षणाय तदाहुरेकं बहुधा योऽवधान्मायया तत्र पुरुषं यश्च तत्रैवम्
rūpaṃ rūpaṃ pratirūpo babhūva tadasya rūpaṃ praticakṣaṇāya tadāhurekaṃ bahudhā yo'vadhānmāyayā tatra puruṣaṃ yaśca tatraivam
The original form manifested in innumerable forms. By the desire to see that original form, He who is One multiplied Himself into many forms through the power of illusion. There is the Puruṣa, and thus is He.
This verse explores the mystery of manifestation. The Puruṣa, the Supreme Consciousness, is originally One without a second, but through māyā —not as deception but as the creative power of appearance— manifests as the multiplicity of the universe. In our yoga practice, we experience this when we observe how the mind projects innumerable thoughts and forms, while in deep meditation we discover the single witness that presides over all this diversity. The Purusha is not separate from the forms, but sustains them as His own extension.