First published 18 May 2008 · revised and expanded 18 August 2026.
कायरूपसंयमात् तद्ग्राह्यशक्तिस्तम्भे चक्षुःप्रकाशासम्प्रयोगेऽन्तर्धानम्
kāya-rūpa-saṁyamāt tad-grāhya-śakti-stambhe cakṣuḥ-prakāśāsaṁprayoge ’ntardhānam
— Yoga Sūtras III.21
By saṁyama on the form of the body — its power to be grasped suspended, the light of the eye no longer meeting it — invisibility.
Word by word: kāya, the body; rūpa, its form, the visible shape of it; saṁyamāt, from saṁyama; tad-grāhya-śakti-stambhe, upon the arresting (stambha) of its power (śakti) to be grasped (grāhya); cakṣuḥ-prakāśa-asaṁprayoge, upon the non-meeting of eye and light; antardhānam, disappearance — literally a “placing within.”
And saṁyama? Patañjali defines it at the head of this very chapter: trayam ekatra saṁyamaḥ (III.4) — the three, held on one object, are saṁyama. The three being dhāraṇā, holding the mind to one place; dhyāna, the unbroken stream of attention there; and samādhi, absorption so complete the mind seems emptied of itself — the cessation of mindstuffs, as I glossed it when this post was new. Aim that triple lens at anything, says the vibhūti-pāda, and the thing opens.
Word has it that the great Maharishi Mahesh Yogi would sometimes give this siddhi to select members of his meditation group in the early days of the movement. He stopped when it became apparent, so to speak, that the comrades of the disappeared siddhas got upset.
Now look at the engineering in the sutra, because it is precise. It names two distinct things that must happen. First, stambha: the body’s property of being perceivable is itself suspended — something is switched off at the object. Second, asaṁprayoga: the conjunction of the eye and light fails — the channel is cut. Invisibility is defined optically. Not “the body is gone,” but “no light connects this body to an eye.” That is, to the letter, how a physicist would define it today.
When this post was new, the headlines were of Western labs catching up. In 2006 Pendry, Schurig, and Smith published the theoretical blueprint, and the Duke group promptly built it: a metamaterial shell that guides microwaves smoothly around a hidden interior and releases them on the far side as though nothing were there. The rays never meet the object; the observer receives a world with the seam sewn invisibly shut. Cakṣuḥ-prakāśāsaṁprayoga, in split copper rings. The military is, still, catching up.
One more detail for lovers of the text. Some manuscripts follow this sutra with a companion line — etena śabdādy-antardhānam uktam, “by this, the disappearance of sound and the rest is likewise explained.” Engineered silence beside engineered vanishing: no pressure wave meets the ear. (It is because some editions count that line and some do not that sutra numbers drift by one across translations of this chapter.)
A sutra is a thread. This one reads like a specification.
Another saṁyama, another window, published the same day: on the Sun, knowledge of the worlds.