As the mind selects little parcels of energy from the vast “ocean of energy”, that we have talked about earlier, it qualifies them as shape, sound, colour and so on. All this is varna, for varna is the intermediary between the Universal, the Unknown sea of moving energy (the jagatyāmjagat of Isāvāsyam Upanishad)  and our senses. For that which covers also exposes itself; reveals itself to the rest of us. This a very important concept : varnas are therefore units of ākritī, shape/form ; units of colour and they are the units of sound that appear as akśar, letters/phonemes, to our ears or śröt. If we were to take a small piece of clear glass and turn it towards the rising sun – it would partially cover the sun’s rays ; at the same time revealing a red hue and its own outline. This is how the varnas assist our minds in nomenclating and talking about the entire range of māyā.
◊ In a similar vein Percy Bysshe Shelley (1792-1822), an English poet puts it so succinctly : excerpted from an elegy – Adonais (passage # LII) :-
The One remains, the many change and pass ;
Heaven’s light forever shines, Earth’s shadows fly ;
Life, like a dome of many-colored glass,
Stains the white radiance of Eternity,
Until Death tramples it to fragments.– Die,
If thou wouldst be with that which thou dost seek !
Follow where all is fled ! – Rome’s azure sky,
Flowers, ruins, statues, music, words, are weak
The glory they transfuse with fitting truth to speak.
It is the varnas which bring about “Life, like a dome of many-colored glass” into our senses by giving us the instance to talk about and identify the “Flowers, ruins, statues, music, words…”.