Question: During what years did Michelangelo work on David?
About the article "David (Michelangelo)", section "Commission".

Candidate passages:
Some have hypothesized that Michelangelo depicted himself in the flayed skin of St. Bartholomew (see below) based on feelings of contempt Michelangelo may have had for being commissioned to paint "The Last Judgment."
Michelangelo often drew himself in a way where he had lost all his power and might.
He questioned over thoughts of dying and the Day of Judgement, which is seen as a reference to this work.
Michelangelo was in his late sixties when he finished this painting, and it has been argued that the peeling of Bartholomew signifies the peeling of the flesh awaiting a new rebirth.
The bearded figure of St. Bartholomew holding the skin was theorized to depict the satirist and erotic writer Pietro Aretino, who had tried to extort a valuable drawing from Michelangelo; this theory has been conclusively refuted because the conflict between Michelangelo and zed Aretino did not occur until 1545, seven years after the fresco's completion. 
The process took less than two years.
The "Pietà"'s first home was the Chapel of Santa Petronilla, a Roman mausoleum near the south transept of St. Peter's, which the Cardinal chose as his funerary chapel.
The chapel was later demolished by Bramante during his rebuilding of the basilica.
According to Giorgio Vasari, shortly after the installation of his "Pietà" Michelangelo overheard (or asked visitors about the sculptor) someone remark that it was the work of another sculptor, Cristoforo Solari, whereupon Michelangelo signed the sculpture.
Michelangelo carved MICHAELABONAROTUS FLORENTIN[US FACIEBA(Michelangelo Buonarroti, Florentine, made this) on the sash running across Mary's chest.
The signature echoes one used by the ancient Greek artists, Apelles and Polykleitos.
It was the only work he ever signed.
Vasari also reports the anecdote that Michelangelo later regretted his outburst of pride and swore never to sign another work of his hands.
In 1964, The Pietà was lent by The Vatican to the 1964-1965 New York World's Fair to be installed in The Vatican Pavilion.
People stood on line for hours to catch a glimpse from a conveyor belt moving past the masterpiece.
It was returned to The Vatican after the Fair.  
That part of the restoration in the Sistine Chapel which has caused the most concern is the ceiling, painted by Michelangelo.
The emergence of the brightly coloured Ancestors of Christ from the gloom sparked a reaction of fear that the processes being employed in the cleaning were too severe.
Despite warnings, the work on the ceiling proceeded and, according to critics such as James Beck, their worst fears were confirmed once the ceiling was completed.
The cause for dissent lies in the analysis and understanding of the techniques utilised by Michelangelo, and the technical response of the restorers to their understanding of those techniques.
A close examination of the frescoes of the lunettes convinced the restorers that Michelangelo worked exclusively in "buon fresco"; that is, the artist worked only on freshly laid plaster and each section of work was completed while the plaster was still in its fresh state.
In other words, Michelangelo did not work "a secco"; he did not come back later and add details onto the dry plaster.
The restorers, by assuming that the artist took a universal approach to the painting, took a universal approach to the restoration.
A decision was made that all of the shadowy layer of animal glue and "lamp black", all of the wax, and all of the overpainted areas were contamination of one sort or another: smoke deposits, earlier restoration attempts and painted definition by later restorers in attempt to enliven the appearance of the work.
Based on this decision, according to Arguimbau's critical reading of the restoration data that has been provided, the chemists of the restoration team decided upon a solvent that would effectively strip the ceiling down to its paint-impregnated plaster.
After treatment, only that which was painted "buon fresco" would remain.
According to critics, the inherent problem with this approach is that it relied heavily upon an assumption that Michelangelo only painted "buon fresco", that he was always satisfied with the result at the end of the day, and that in four and a half years spent on the ceiling, he stuck exclusively to one approach, and never made small alterations or added details.
Arguimbau, on his website, quotes Colalucci, the head of the team, as contradicting himself on this matter.
A summary of the relevant statements of Colalucci, in the order that they occur in the Appendix entitled "Michelangelo's colours uncovered" is as follows: The elderly restorers who had taken part in the restoration of the 1930s were interviewed as part of the preparatory process.
They claimed that Michelangelo worked over the frescoes "a secco" using "velature" or glazes as a binder.
Colalucci rejects this, stating that Michelangelo worked exclusively in "buon fresco".
Colalucci then contradicts this by stating that Michelangelo had worked "a secco", but "to a minimal degree" and "not at all in the lunettes".
Colalucci then talks of Michelangelo's "rigorous maintenance" of "buon fresco" technique, contradicting this by describing the "a secco" retouchings that Michelangelo made to the shoulder of Eleazar and the foot of Reboam, both of which are in the lunettes.
He then says that Michelangelo worked in "buon fresco" with "no "pentimenti" proper", (pentimenti means the changes) but only small corrections in fresco.
The on-going criticism has been that the restorers presumed to know what end result the master was seeking to achieve in every separate case across the ceiling, and by what method he sought to achieve it.
The disagreements about this have been vociferous and are unresolved. 
To be able to reach the ceiling, Michelangelo needed a support; the first idea was by Julius' favoured architect Donato Bramante, who wanted to build for him a scaffold to be suspended in the air with ropes.
However, Bramante did not successfully complete the task, and the structure he built was flawed.
He had perforated the vault in order to lower strings to secure the scaffold.
Michelangelo laughed when he saw the structure, and believed it would leave holes in the ceiling once the work was ended.
He asked Bramante what was to happen when the painter reached the perforations, but the architect had no answer.
The matter was taken before the Pope, who ordered Michelangelo to build a scaffold of his own.
Michelangelo created a flat wooden platform on brackets built out from holes in the wall, high up near the top of the windows.
Contrary to popular belief, he did not lie on this scaffolding while he painted, but painted from a standing position.
Michelangelo used bright colours, easily visible from the floor.
On the lowest part of the ceiling he painted the ancestors of Christ.
Above this he alternated male and female prophets, with Jonah over the altar.
On the highest section, Michelangelo painted nine stories from the Book of Genesis.
He was originally commissioned to paint only 12 figures, the Apostles.
He turned down the commission because he saw himself as a sculptor, not a painter.
The Pope offered to allow Michelangelo to paint biblical scenes of his own choice as a compromise.
After the work was finished, there were more than 300.
His figures showed the creation, Adam and Eve in the Garden of Eden, and the Great Flood.
The painted area is about 40 m (131 ft) long by 13 m (43 ft) wide.
This means that Michelangelo painted well over of frescoes. 
Upon its initial release, "Intolerance" was a commercial failure.
Despite this, "Intolerance" has received very positive reviews.
"Intolerance" has been called "the only film fugue".
Professor Theodore Huff, one of the leading film critics of the first half of the 20th century, stated that it was the only motion picture worthy of taking its place alongside "Beethoven's Fifth Symphony", the masterpieces of Michelangelo, etc.
as a separate work of art.
The film was shown out of competition at the 1982 Cannes Film Festival.
In 1989, "Intolerance" was selected for preservation in the United States National Film Registry by the Library of Congress as being "culturally, historically, or aesthetically significant", going in during the first year of voting.
In 2007, AFI's 100 Years...100 Movies (10th Anniversary Edition) ranked "Intolerance" at number 49 of 100 films.
The film currently holds a 96% approval rating on the aggregate site Rotten Tomatoes.
Film critic David Thomson has written of the film's "self-destructive frenzy":The cross-cutting, self-interrupting format is wearisome...
The sheer pretension is a roadblock, and one longs for the "Modern Story" to hold the screen... story is still very exciting in terms of its cross-cutting in the attempt to save the boy from the gallows.
This episode is what Griffith did best: brilliant, modern suspense, geared up to rapidity — whenever Griffith let himself slow down he was yielding to bathos...
Anyone concerned with film history has to see "Intolerance", and pass on.