अथान्यत्राप्युक्तम् ब्रह्मणो वा वैतत्तेजः परस्यामृतस्याशरीरस्य यच्छरीरस्यौष्ण्यमस्यैतद् घृतमथाविः सन् नभसि निहितं वैतदेकाग्रेणैवमन्तर्हृदयाकाशं विनुदन्ति यत्तस्य ज्योतिरिव सम्पद्यतीति अतस्तद्भावम् अचइरेणैति भूमावयस्पिण्डं निहितं यथाऽचिरेणैति भूमित्वम् मृद्वत्संस्थमयस्पिण्डं यथाग्न्ययस्कारादयो नाभिभवन्ति प्रणश्यति चित्तं तथाश्रयेण सहैवमित्येवं ह्याह हृद्याकाशमयं कोशमानन्दं परमालयम् ।स्वं योगश्च ततोऽस्माकं तेजश्चैवाग्निसूर्ययोः ॥ ॥६.२७ ॥
In plain words
And it is said elsewhere too: This is the splendour of Brahman, of the highest, the immortal, the bodiless — and the warmth of the body is its ghee. Though manifest, it is set down in the sky as though hidden; and by one-pointedness they thrust apart the space within the heart, so that what is like its light comes forth. So a man swiftly comes to be of its nature: as a lump of iron set in the earth swiftly comes to be earth, and as fire and smiths and the rest do not overpower a lump of iron that has settled into the state of clay, so thought perishes together with that in which it rests. So it is said: "The sheath within the heart, made of space, blissful, the highest abode — that is our own, and our discipline, and the splendour of fire and of the sun."