Minimalism wasn't a real idea - it ended before it started.
Most ideas that are successful are ludicrously simple
In conceptual art the idea or concept is the most important aspect of the work
Buying books was a way anyone could acquire a work of art for very little.
The idea becomes a machine that makes the art.
When words such as painting and sculpture are used, they connote a whole tradition and imply a consequent acceptance of this tradition, thus placing limitations on the artist who would be reluctant to make art that goes beyond the limitations.