Marcel Duchamp's Three Great Putative Gestures were:

 
1. Adding a moustache and beard to the Mona Lisa in L.H.O.O.Q (1919);

2. Bottling Paris air (1919);

3. The creation with Man Ray's help of his artistic alter-ego, Rrose Selavy (1920 and 1921), who featured on an empty perfume bottle, whose purpose was to provide a bottled version of the artist.

 

Marcel Duchamp Three Standard Stoppages

 

Marcel Duchamp Three Standard Stoppages

 

Combined, these gestures (for that is what they were as opposed to works of art in the official sense) managed to express the world to come, although it would not be until the 1960s when this became entirely evident.