Light

from a Shloka on Lord Vinayaka -Vakratunda mahAkAya sUryakoTi samaprabha… means O lord Vinayaka with a curved trunk and a massive body, your form equals the Light of a Crore Suns!!!
from nAma rAmayaNa - …tEjOmaya nija rUpaka rAm means O rAma your real form is full of Light
from aruNAchala pancharatnam -

…kabalitha ghana vishvarUpakiraNAvalya… means O aruNAchala you’ve swallowed the world with your light

and …dIdhitimaruNAchalatvaimahIyanthe means (… means when one dives within) you’ll be seen as Light extending till the end of the world

what all these mean to say is that the truth is just Light!!!

sarvam ramaNArpaNamastu.

Jai Sadguru Ramana.