There are two very different types of artists: those I call Old Masters, who work by trial and error and tend to improve with age, and conceptual people, or Young Geniuses, who generally do their best work early in their careers.

Artists who have produced experimental innovations have been motivated by aesthetic criteria: they have aimed at presenting visual perceptions. Their goals are imprecise, so their procedure is tentative and incremental.

Titian and Rembrandt, Monet and Rodin, Frank Lloyd Wright and Le Corbusier, Mark Twain and Henry James, Robert Frost and Elizabeth Bishop, to name a few. Twain wrote 'Tom Sawyer' at 41 and bettered it with 'Huckleberry Finn' at 50 Wright completed Fallingwater at 72 and worked on the Guggenheim Museum until his death at 91.

It's not curators, it's not critics, it's not the public, it's not collectors who find great artists - it's other artists.

Artists have made innovations in many areas... But whatever the nature of an artist's innovation, its importance ultimately depends on the extent of its influence on other artists.

The people who do better and better work are people who are never satisfied. Cezanne would say, 'I think I've accomplished something,' but then he would immediately add, 'But it's not enough.