”Making one’s own self the lesser wood-stick and the Supersoul the superior wood-stick, the regular spiritual practice is to be the constant rubbing of them together so one should endeavor to bring out the hidden fire-like Supreme Lord from within in order to see Him.”
sva-deham aranim krtva
pranavam cottararanim
dhyana nirmathanabhyasad
devam pasyen nigudha vat
PURPORT BY SRI KRSNA BALARAM SWAMIJI
In olden days two pieces of wood sticks were rubbed together very hard to bring out the dormant fire hidden from inside the wood and no match was used to ignite the wood. This human birth is very difficult to obtain again but we already have it, sages suggested that, we should use it to behold the Supreme Lord. Just as one wood-stick is kept on the ground to rub upon with another wood-stick to bring out fire, similarly one should become a steady devotee and constantly practice spiritual life of chanting the holy names of the Lord so the Supreme Lord seated inside the heart in the form of the Supersoul can manifest clearly before the soul.
[Svetasvatara Upanisad, 1.14, KBS0010]