The noise of metal on metal
"But the skill that thrilled her the most was her ability to take apart and re-assemble internal combustion engines. The smell of burning diesel or petrol was the most intoxicating perfume. The noise of machines in a workshop, of iron drilling onto iron, of iron filing iron, of iron hammering on iron, of workers raising their voices above the noise of metal on metal - to Wariinga these noises were like a beautiful song sung by the best of choirs" -Ngũgĩ Wa Thiong’o, Devil On The Cross
