कायरूपसंयमात् तत्ग्राह्यशक्तिस्तम्भे चक्षुः प्रकाशासंप्रयोगेऽन्तर्धानम् ॥२१॥
kāya-rūpa-saṁyamāt tat-grāhyaśakti-stambhe cakṣuḥ prakāśāsaṁprayoge-'ntardhānam ||21||

[RS] 3.21 Through meditation on the form of one's own physical body, it becomes possible to impede the capacity that renders the body visible. This precludes a connection between light and the eyes and renders the body invisible to others.

[JW] 3.21 As a result of constraint upon the [outer] form of the body, when its power to be known is stopped, then as a consequence of the disjunction of the light and of the eye there follows indiscernibility [of the yogin's body].

[SS] 3.21 By samyama on the form of one's body, [and by] checking the power of perception by intercepting light from the eyes of the observer, the body becomes invisible. [p186]

[EB] 3.21 By performing samyama on the outer form of the body, invisibility [is attained]. This occurs when perceptibility is obstructed by blocking contact between light and the eyes. [p347]

<Page 3.20    Page 3.22>

(काय, kāya) = body
(रूप, rūpa) = form
(संयमात्, saṁyamāt) = by practicing contemplation; samyama; meditation
(तत्, tat) = that
(ग्राह्य, grāhya) = perceptible
(शक्ति, śakti) = power; capacity
(अर्ह्तः, arhtaḥ) = impediment
(चक्षुः, cakṣuḥ) = eye
(प्रकाश, prakāśa) = light
(असंप्रयोगे, asaṁprayoge) = no connection
(अन्तर्धानम्, antardhānam) = disappear; invisibility