13.18 Tat, that Knowable; is the jyotih, Light; api, even; jyotisam, of the lights-of the sun etc. For the lights like the sun etc. shine because they are enkindled by the light of consciousness of the Self, as is known from Upanisadic texts like, 'Illumined by whose light the sun shines' (Tai. Br. 3.12.9.7), 'By Its light all this shines variously' (Sv. 6.14), and from the Smrti also, as here (in the Gita) itself: 'That light in the sun৷৷.' (15.12), etc.
It is ucyate, spoken of as; param, beyond, untouched by; tamasah, darkness; ignorance. For cheering up anyone who may become disheartened by thinking that Knowledge etc. is difficult to attain, the Lord says: It is jnanam, Knowledge-humility etc. (verse 7, etc.); jneyam, the Knowable, which has been spoken of in, 'I shall speak of that which is to be known' (12); and jnana-gamyam, the Known. The Knowable itself is referred to as jnanagamyam, when after being known, It becomes the result of Knowledge. But when It is an object to be known, It is called jneyam. All these three which are such, visthitam, specially exist; hrdi, in the hearts, in the intellects; sarvasya, of all, of all creatures.
For these three are, indeed, perceived there.
 
This verse is begun for concluding the topic under discussion: