Patanjali's yoga sutras

कायरूपसंयमात्तद्ग्राह्यशक्तिस्तम्भे चक्षुःप्रकाशासंप्रयोगेऽन्तर्धानम् ॥ ३.२१॥

3.21 kāyarūpasamyamāttadgrāhyaśaktistambhe caksuhprakāśāsamprayoge’ntardhānam

kāya = body

rupa = form

samyamā = meditation

tat = that

grahya = to be seen

shakti = power

tat = that

stambhe = obstruct

chaksuh = sight

prakasha = light

asamprayoga = non-contact with

antardhanam = invisibility

By meditating on the form of your body as perceived by others, you gain the power to obstruct their sight. If there is no contact between your body and the light, you are invisible.