Cartier-Bresson’s concept of the “decisive moment” — a split second that reveals the larger truth of a situation — shaped modern street photography and set the stage for hundreds of photojournalists to bring the world into living rooms.

Photographs are no longer rare artifacts, nor primarily a means of learning about the exotic or unknown. They arrive instantaneously on our phones every day from every corner of the world and from all kinds of people. With a smart phone, everyone is a photographer, and images compete for crowd approval on social media channels like Instagram, Snapchat and Facebook.

Which raises questions on this anniversary of Cartier-Bresson’s death: Do these changes make a master’s carefully constructed images irrelevant? Or are they even more instructive today?