Thic Sun representing light is Goodness; the heat is the quality of Darkness; the shading (or eclipse) of the Sun on Parvan days, should be known to represent Ignorance.
प्रकाश्यं सत्त्वमादित्यः संतापो रजसो गुणः। उपप्लवस्तु विज्ञेयस्तामसस्तस्य पर्वसु॥