“Your question as to why we use light bulbs, is answered as follows: light bulbs are also a part of Kṛṣṇa’s energy. Just as we use automobiles, adding machines, typewriters, dictaphone etc. Whatever is there should be employed in service of Kṛṣṇa. Without using matter in service of Kṛṣṇa it becomes the cause of bondage, but by using it in the service of Krsna it helps us to become Kṛṣṇa conscious."
-Śrila Prabhupāda’s Letter to Eric written from Dallas, May 20, 1973