Before the light bulb was invented, people had figured out how to put a reflector behind it, focus it a little bit; put lenses in front of it, focus it a little bit better.
Sebelum bola lampu ditemukan, orang-orang memasang pemantul cahaya di belakangnya, sedikit memfokuskannya; dan menaruh lensa di depannya, memfokuskannya lagi.