Text:

वायुर्यथैको भुवनं प्रविष्टो रूपं रूपं प्रतिरूपो बभूव ।
एकस्तथा सर्वभूतान्तरात्मा रूपं रूपं प्रतिरूपो बहिश्च ॥ १० ॥

vāyuryathaiko bhuvanaṃ praviṣṭo rūpaṃ rūpaṃ pratirūpo babhūva |
ekastathā sarvabhūtāntarātmā rūpaṃ rūpaṃ pratirūpo bahiśca || 10 ||

10. As wind, though one, having entered the world, assumes forms responsive to every form, so the internal atman of all living things, though one, assumes forms responsive to every form and is outside them all.

Shankara’s Commentary:

So, another illustration (is offered by ‘as wind though one’, etc.). The analogy is complete, as he enters all bodies as pratta and takes forms corresponding to every form.