Once it is out of his hand the artist has no control over the way a viewer will perceive the work. Different people will understand the same thing in a different way.
Sol LeWittAn architect doesn't go off with a shovel and dig his foundation and lay every brick. He's still an artist.
Sol LeWittWhen an artist uses a conceptual form of art, it means that all of the planning and decisions are made beforehand and the execution is a perfunctory affair. The idea becomes a machine that makes the art.
Sol LeWitt