Verse 8.6.1

अथ या एता हृदयस्य नाड्यस्ताः पिङ्गलस्याणिम्नस्तिष्ठन्ति शुक्लस्य नीलस्य पीतस्य लोहितस्येत्यसौ वा आदित्यः पिङ्गल एष शुक्ल एष नील एष पीत एष लोहितः ॥ ८.६.१ ॥

atha yā etā hṛdayasya nāḍyastāḥ piṅgalasyāṇimnastiṣṭhanti śuklasya nīlasya pītasya lohitasyetyasau vā ādityaḥ piṅgala eṣa śukla eṣa nīla eṣa pīta eṣa lohitaḥ || 8.6.1 ||

1. Then these veins connected with the heart are each filled with a thin liquid, coloured reddish-yellow, white, blue, yellow, and red. The sun there also has these colours—reddish-yellow, white, blue, yellow, and red.

Word-for-word explanation:

Atha, then; yaḥ etāḥ hṛdayasya nāḍyaḥ, these veins which are in the heart; taḥ, they; piṅgalasya aṇimnaḥ tiṣṭhanti, are filled with a very thin, tawny-coloured liquid; śuklasya, of white; nīlasya, of blue; pītasya, of yellow; lohitasya iti, of red; asau vai ādityaḥ, the sun there; piṅgalaḥ, is tawny; eṣaḥ śuklaḥ, it is white; eṣaḥ nīlaḥ, it is blue; eṣaḥ pītaḥ, it is yellow; eṣaḥ lohitaḥ, it is red.

Commentary:

The heart is the place where one meditates on Brahman. The heart is said to be shaped like a lotus bud, and it also has some similarities to the sun. The sun emits its rays, which spread out in all directions. Similarly, the veins arise from the heart and spread out in all directions. These veins are filled with a very thin substance. This substance changes its colour, and along with it, the veins also change colour. Sometimes it is reddish-yellow, sometimes blue, sometimes white, etc. The sun changes its colour likewise.