Abstract or non-representational art, like Mondrian's paintings, is constituted of forms and colors that represent nothing in visible reality, although one might say that the lines represent abstract lines or abstract geometrical shapes). 

This painting is self-aware to the extent that lines are the means by which painter's construct representations rather than conventional objects of representation.  

Abstract and non-representational art implicitly or explicitly puts into question the presupposition that painting should represent real  people, things, situations or that paintings of fictional scenes (see Poussin's "Orphyus and Eurydice") should include, if not be limited to, realistic representations of people, things, or situations.

Encyclopedia Britannica

ABSTRACT ART

Also called NONOBJECTIVE ART, or NONREPRESENTATIONAL
ART, painting, sculpture, or graphic art in which the portrayal of things
from the visible world plays no part. All art consists largely of elements
that can be called abstract--elements of form, colour, line, tone, and
texture. Prior to the 20th century these abstract elements were
employed by artists to describe, illustrate, or reproduce the world of
nature and of human civilization--and exposition dominated over
expressive function.




Abstract art has its origins in the 19th century. The period characterized
by so vast a body of elaborately representational art produced for the
sake of illustrating anecdote also produced a number of painters who
examined the mechanism of light and visual perception. The period of
Romanticism had put forward ideas about art that denied classicism's
emphasis on imitation and idealization and had instead stressed the role of
imagination and of the unconscious as the essential creative factors.
Gradually many painters of this period began to accept the new freedom
and the new responsibilities implied in the coalescence of these attitudes.
Maurice Denis's statement of 1890, "It should be remembered that a
picture--before being a war-horse, a nude, or an anecdote of some
sort--is essentially a flat surface covered with colours assembled in a
certain order," summarizes the feeling among the Symbolist and
Postimpressionist artists of his time.




All the major movements of the first two decades of the 20th century,
including Fauvism, Expressionism, Cubism, and Futurism, in some way
emphasized the gap between art and natural appearances.




There is, however, a deep distinction between abstracting from
appearances, even if to the point of unrecognizability, and making works
of art out of forms not drawn from the visible world. During the four or
five years preceding World War I, such artists as Robert Delaunay,
Wassily Kandinsky, Kazimir Malevich, and Vladimir Tatlin turned to
fundamentally abstract art. (Kandinsky is generally regarded as having
been the first modern artist to paint purely abstract pictures containing
no recognizable objects, in 1910-11.) The majority of even the
progressive artists regarded the abandonment of every degree of
representation with disfavour, however. During World War I the
emergence of the de Stijl group in The Netherlands and of the Dada
group in Zürich further widened the spectrum of abstract art.




Abstract art did not flourish between World Wars I and II. Beset by
totalitarian politics and by art movements placing renewed emphasis on
imagery, such as Surrealism and socially critical Realism, it received little
notice. But after World War II an energetic American school of abstract
painting called Abstract Expressionism emerged and had wide influence.
Since the 1950s abstract art has been an accepted and widely
practiced approach within European and American painting and
sculpture. Abstract art has puzzled and indeed confused many people,
but for those who have accepted its nonreferential language there is no
doubt as to its value and achievements.