Sergey Brin stared at the eleven different sauces available, and considered the geometric explosion of combinations possible. «If someone asks me to find them a sauce recommendation for their delicious Subway-brand submarine sandwich, I could return to them with a more relevant search result if I first considered what sauces other patrons have tacitly recommend in the past by ordering them for themselves,» he realized. It was a stunning insight, and the world would never be the same. The small part of the world concerned with improved relevancy in sub sauce recommendations would never be the same.