Fed up with being hounded by the New York State attorney general’s office over alleged zoning violations in the early 1970s, George Maciunas, the real estate developer, graphic artist and leading light of Fluxus, the international network of Conceptual artists, created an artwork that doubled as a defense against subpoena-wielding enforcers. He attached four industrial-size paper-cutting blades to the grungy yellow front door of his Manhattan apartment.

In a 1975 issue of his Fluxus Newsletter, Maciunas (pronounced ma-CHEW-nus) described his “event in progress,” or “Flux Combat with New York State Attorney (& police).” Therein he itemized his “arsenal of weapons,” which consisted of “humorous, insulting and sneering letters to the attorney general” and his “Flux Fortress,” which included the bladed front door and, for intruders who got past that, booby traps and “funny messages” left behind trick doors and hatches.

That front door is now on view in “Fluxus and the Essential Questions of Life,” at the Grey Art Gallery, New York University. It is a historically fascinating and excellently produced show of works that mostly masked revolutionary intentions behind deceptively modest, small-scale pieces of assemblage, print making, performance and wordplay.