Text 19

yatha dipo nivata-stho
nengate sopama smrta
yogino yata-cittasya
yunjato yogam atmanah

Translation

As a lamp in a windless place does not waver, so the transcendentalist, whose mind is controlled, remains always steady in his meditation on the transcendent self. 

Commentary by Srila Prabhupada 

A truly Krishna conscious person, always absorbed in transcendence, in constant undisturbed meditation on his worshipable Lord, is as steady as a lamp in a windless place.

Commentary by Sri Visvanatha Cakravarti Thakur

It is considered exactly (yatha) similar (upama) to the lamp, which does not move (na ingate) when in a windless place (nivata sthah). The elision of sa with upama is according to the rule so'ci lope cet pada-puranam. (Panini 6.1.134) What is the comparison? It is compared to the consciousness of the yogi, devoid of movement.