In 1917 Picasso went to Rome to design costumes and scenery for a Russian ballet company. During this period he fell back to classical forms and painting techniques but never gave up experimenting with cubism.
Blue and Rose period
The Picasso art period known as the Blue Period extended from 1901 to 1904. During this time, the artist painted primarily in shades of blue, with occasional touches of accent color. For example, the famous 1903 artwork, The Old Guitarist, features a guitar in warmer brown tones amid the blue hues. Picasso‘s Blue Period works are often perceived as somber due to their subdued tones.
Picasso attended the School of Fine Arts in Barcelona, where his father taught, at 13 years of age. In 1897, Picasso began his studies at Madrid’s Real Academia de Bellas Artes de San Fernando, which was Spain’s top art academy at the time. Picasso attended only briefly, preferring to roam the art exhibits at the Prado, studying works by El Greco, Francisco Goya, Diego Veláquez and Zurbáran.
After Cubism, Picasso explored classical and Mediterranean themes, and images of violence and anguish increasingly appeared in his work. In 1937, this trend culminated in the masterpiece Guernica, a monumental work that evoked the horror and suffering endured by the Basque town of Guernica when it was destroyed by German war planes during the Spanish Civil War. Picasso remained in Paris during the Nazi occupation but was fervently opposed to fascism and after the war joined the French Communist Party.
In Cubism, which is divided into two phases, analytical and synthetic, Picasso and Braque established the modern principle that artwork need not represent reality to have artistic value. Major Cubist works by Picasso included his costumes and sets for Sergey Diaghilev’s Ballets Russes (1917) and The Three Musicians (1921). Picasso and Braque’s Cubist experiments also resulted in the invention of several new artistic techniques, including collage.
The body of work Picasso created throughout his lifetime is enormous and spans from his early childhood years until his death, creating a more comprehensive record of his development than perhaps any other artist. When examining the records of his early work there is said to be a shift where the child-like quality of his drawings vanished, therefore being the official beginning of his career. That date is said to be 1894, when Picasso was just 13. At the age of 14 he painted Portrait of Aunt Pepa, a striking depiction that has been referred to as one of the best portraits in Spanish history. And at age 16, Picasso created his award-winning Science and Charity.
When Les Demoiselles d’Avignon first appeared, it was as if the art world had collapsed. Known form and representation were completely abandoned. Hence it was called the most innovative painting in modern art history. With the new strategies applied in the painting, Picasso suddenly found freedom of expression away from current and classical French influences and was able to carve his own path. Formal ideas developed during this period lead directly into the Cubist period that follows.
Between 1915 and 1917, Picasso began a series of paintings depicting highly geometric and minimalist Cubist objects, consisting of either a pipe, a guitar or a glass, with an occasional element of collage. “Hard-edged square-cut diamonds”, notes art historian John Richardson, “these gems do not always have upside or downside”.   “We need a new name to designate them,” wrote Picasso to Gertrude Stein: Maurice Raynal suggested “Crystal Cubism”.   These “little gems” may have been produced by Picasso in response to critics who had claimed his defection from the movement, through his experimentation with classicism within the so-called return to order following the war.  
After returning from his honeymoon and in need of money, Picasso started his exclusive relationship with the French-Jewish art dealer Paul Rosenberg. As part of his first duties, Rosenberg agreed to rent the couple an apartment in Paris at his own expense, which was located next to his own house. This was the start of a deep brother-like friendship between two very different men, that would last until the outbreak of World War II.