Arnold Schwarzenegger in a Lesson in Secondary School, 1958

The photograph shows Arnold Schwarzenegger In A Lesson In Secondary School, 1958. Made in 1958, it is the kind of image that turns a date in a history book into something you can actually see.

The 1950s brought a wave of postwar prosperity, especially in North America. Suburbs, television sets, big chrome-trimmed cars, and rock and roll defined the decade, and a booming picture-magazine industry sent photographers to document all of it.

Pictures of ordinary life are some of the most valuable historical documents we have. Grand events were always going to be recorded, but a normal day — how people worked, dressed, shopped, and passed the time — survives only when someone happened to point a camera at it.