SB 6.3.16
yam vai na gobhir manasasubhir va
hrda gira vasu-bhrto vicaksate
atmanam antar-hrdi santam atmanam
caksur yathaivakrtayas tatah param
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
As the different limbs of the body cannot see the eyes, the living entities cannot see the Supreme Lord, who is situated as the Supersoul in everyone’s heart. Not by the senses, by the mind, by the life air, by thoughts within the heart, or by the vibration of words can the living entities ascertain the real situation of the Supreme Lord.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Although the different parts of the body do not have the power to see the eyes, the eyes direct the movements of the body’s different parts. The legs move forward because the eyes see what is in front of them, and the hand touches because the eyes see touchable entities. Similarly, every living being acts according to the direction of the Supersoul, who is situated within the heart. As the Lord Himself confirms in Bhagavad-gita (15.15), sarvasya caham hrdi sannivisto mattah smrtir jñanam apohanam ca: “I am sitting in everyone’s heart and giving directions for remembrance, knowledge and forgetfulness.” Elsewhere in Bhagavad-gita it is stated, isvarah sarva-bhutanam hrd-dese ’rjuna tisthati: “The Supreme Lord, as the Supersoul, is situated within the heart.” The living entity cannot do anything without the sanction of the Supersoul. The Supersoul is acting at every moment, but the living entity cannot understand the form and activities of the Supersoul by manipulating his senses. The example of the eyes and the bodily limbs is very appropriate. If the limbs could see, they could walk forward without the help of the eyes, but that is impossible. Although one cannot see the Supersoul in one’s heart through sensual activities, His direction is necessary.