century. Permits are renewable, artists often complete more than one session. Copyists are still required to follow certain traditions such as being required to cover the floor with a drop cloth to prevent damage to the gallery floors at the MET. Notable artists such as Picasso began practising their art as copyists in museums. The utility of this programme has frequently been emphasised, for instance artists such as Paul Cézanne and Cennino Cennini in The Book of Art. Ingres and Delacroix highly emphasised the value of learning from other painters by going to the Louvre and discovering their artistic personalities. The benefits of copying were addressed in a study by Okada and Ishibashi (2004). It was found that copying caused the participants to assess and compare their own artistic style with others, which led to more creative pieces, in comparison to the control group. Permits At some centres the availability of permits has drastically reduced over time due to the popularity of the programme. There are now selection processes involving the submission of a portfolio, along with a list of potential pieces the artist would like to copy. Upon a successful application, artists are normally able to copy their first or second choice. The permits tend to be given to locals, since the artists will be required to spend a lot of time in the gallery. Some of the following museums who grant permits are all subject to different regulations: Metropolitan Museum of Art Louvre Museo Nacional del Prado Some copyists used to be able to make a living from selling their copies made in the Prado, however copyists find it much harder to do this in the 21st century. Art selection The museums allow artists to pick from a variety of different pieces in their collection. Their selection is subject to certain conditions, such as safety concerns and whether the piece is in the permanent collection. In 1880, only two copyists were allowed at paint the Mona Lisa in the Louvre at one time, due to its popularity. The Prado forbids the copying of certain works, such as Las Meninas, which attract crowds. Forgeries Artists frequently only paint a selected area of the work, due to time constraints or individualistic stylistic decisions. However, to discourage and prevent the sale of exact forgeries, the copy must be different in size or scale. At the MET, the copyist's work must be