By the mid-1960s modern architecture had become an official language, governed by its founders' principles — purified volume, the rejection of ornament, 'less is more'. Robert Venturi's *Complexity and Contradiction in Architecture*, published in 1966, objects to that language from within. Drawing examples from history — mannerist façades, baroque churches, ordinary American houses — Venturi argues that architecture's power lies in ambiguity, layering and the capacity to hold contradiction. He answers Mies's 'less is more' with 'less is a bore'.

The house he designed for his mother in the same years is that thesis built: a pediment that looks drawn by a child, split down the middle, contradicting the chimney behind it. The house both uses the familiar image of 'house' and breaks it — saying, against modernism's claim to begin from zero, that architecture speaks to the viewer's memory.

*Learning from Las Vegas*, written in 1972 with Denise Scott Brown and Steven Izenour, is the second step. With their students they mapped the Las Vegas strip and studied the parking lot, the sign and the motel façade with academic seriousness. The result is the distinction between the 'duck' (a building whose form carries its message) and the 'decorated shed' (an ordinary structure with a communicating façade); architecture's business of carrying meaning is made legitimate again. Together the two books supplied the theory of postmodernism — and when some of its 1980s applications turned into shallow historical quotation, Venturi distanced himself from his own legacy. What lasts is not a form but a question: whose language does architecture speak?