Would you rather go deaf or blind?

Looking at the photographs of William Eggleston, you know the answer. His work exults in seeing: colour, shade, the way sunlight moves.

A Memphis native, Eggleston found majesty everywhere. Anywhere. His pictures, which are currently on display at a career-spanning National Portrait Gallery show, catapult you straight into the slow rhythm of an erstwhile American South.

Eggleston was a flâneur. He chose his subjects spontaneously, catching them unaware, never imposing a narrative. Diners, gas stations, Old Timers on the Bayou, club-kids, mechanics, friends, a lover in the grass. Ordinary unremarkable stuff. “There is no particular reason to search for meaning”, he said.

Eggleston's Untitled, c1970, Devoe Money in Jackson, Mississippi © Eggleston Artistic Trust

In the 60s, Eggleston worked in black and white - all serious photographers did - and you'll see these early images at the start of the show.

He looked to Robert Frank and Henri Cartier-Bresson, whose formalist, monochromatic portraits were the definition of fine photography.

The use of colour cheapened photos. It was preserve of the crass Ad-Man, "prejudicing the achievement of life and movement", as Cartier-Bresson said. Robert Frank assured the world that "the colours of photography are black and white".

William Eggleston, Biloxi, Mississippi, 1972 © Eggleston Artistic Trust

In the mid-60s, though, Eggleston began experimenting with colour. By the end of the decade he was almost exclusively using chromatic film. His '76 MoMA solo show was a historic moment: it legitimised colour-photography as a Fine Art form.

When you're standing in front of an Eggleston picture, the heightened, frenzied palette takes you straight to some tiny stolen 50 year-old moment, somewhere in the Deep South. The result is pure poetry. Walking out of the gallery, you look around. The world's suddenly full of magic.