No one knows the exact age of which he started painting but the real question is 'Why did he start painting?'
A near death experience happened
Velazque was about 60 years old when the painting was finished in 1659, the year before his death.
It is a non-figurative painting. It means it does not depict or represent anything. It is a painting - not a painting of anything.
The Foreground in a painting usally is the object closer or nearest the front of the painting.
Death of Marat
Jacques-Louis David immortalized the French Revolutionary Jean-Paul Marat in his painting The Death of Marat. Marat was murdered by Charlotte Corday.
Surprisingly, perhaps, for a piece of art, the title of the piece actually describes what is shows. In the "Death of Marat", Jacques Louis David paints the scene of Jean-Paul Marat's assassination, which took place while Marat was bathing.
The Death of Marat was created in 1793.
Self-sacrifice.
One presumes you mean, in David's painting of the Death of Marat. The letter in his hand is from Charlotte Corday (the girl who stabbed him), making an appointment for the fatal meeting.
The dead man in the painting, Jean-Paul Marat, was a comrade of the artist, Jacques-Louis David, during the French Revolution. Marat was a journalist and a radical who was known for rallying people for the revolt, and was ultimately murdered by Charlotte Corday, (mentioned in the note Marat is holding in the painting). Corday felt that by killing Marat, thousands of deaths in the name of the revolution could be avoided. The purpose could be interpreted as a memorial to the artist's friend as well as a political statement for the horrendous occurrences brought about from the French Revolution.
The painting "The Death of Marat" by Jacques-Louis David depicts the murdered French revolutionary leader Jean-Paul Marat in his bath. The artwork captures the tragic moment when Marat was assassinated by Charlotte Corday in 1793.
The reactions of viewers in the Salon to a painting of Marat addressing the people would depend on who the viewers were. If, for example, they were followers of Marat's, they would probably not have the same reaction as people who wer not his followers.
I don't recall a painting by Goya with this subject matter. Perhaps you are thinking of The Death of Marat by Jacques-Louis David? This was painted in 1793 and is in the Royal Museum of Fine Arts in Brussels.
Probably in 1506, but some rumours say that Leonardo kept 'improving' the painting. That is why he kept it until his death. When he knew he was aboout to die he finished the Mona Lisa and showed everyone her smile. He said it made him think of his wife
The painting is kept in the Louvre Museum(Paris, France).