Picasso is one of the founders of cubism. At first he wrote in a realistic manner, but then, not satisfied with this, he began to gradually break up realism into its constituent parts, together with the images as if dissecting the universe. This can be seen in his work, if you look at them sequentially.
The first of them are realistic and show the world in its entirety (or try). Then they gradually begin to simplify, becoming more and more sketchy. First, the volume disappears, leaving only the planes that move in place of the balls and cubes.
It is difficult to make out the plot in them, but there is one, and if you look correctly, you can see the dynamics, which are far from always characteristic of three-dimensional images. Then the volume that the planes could give also disappears and the pattern becomes irrevocably two-dimensional. He begins to express the main idea in lines, without looking back at the principles of academism and acting exclusively in the interests of the goal.
After that, there are only colored spots in which you can still see the plot - sometimes more expressive than other artists who create in a more conservative manner. When all this path was covered, Picasso returned to realism with new knowledge, as if jumping over all the distance traveled in one jump.
His “Woman with a Guitar” is a creation of the penultimate period. There is nothing voluminous in it; it is, in fact, just a figure of black and white bounded by several lines. But, meanwhile, it is clear that she holds the guitar affectionately, like a child, that she is pleased with herself and the smile on her lips is tender, sweet, despite the fact that it is indicated only by a couple of poems. It seems that a woman should sing - and a pure melody will flow, devoid of meaning, plot, and words, which is only harmony.