After the wholly regular grid-plan of Fig. 1, Mondrian embarked on a new series of works in which the planes differ in terms of form.
A composition expressed as a chromatic variation of the same measurements (Fig. 1) gives way to a space where there is change even in the size and shape of the colored planes (Fig. 2). If in 1919 multiplicity was expressed by color only, now it is expressed expressed both through color and through form.
In Composition B Mondrian adopts a constant module serving to establish a more controlled rhythm in the alternation of planes. We note two contiguous yellow planes of rectangular proportions verging on squares. The same shape reappears lower down once in red and once in light gray. On the right, a large blue area proves to be the sum of the initial module repeated twice vertically. Lower down we have three rectangles – one yellow, one black, and one dark gray – presenting proportions that are half the initial module:

Composition B, 1920, Oil on Canvas, cm. 57,5 x 67

Composition B, 1920, Diagram
Fig. 2a: Though different both in color and in size, these planes are based on the same parameter. Each is an expansion or contraction, either vertical or horizontal, of a pre-established unit of measurement. The planes close to the edges of the canvas suddenly assume instead anomalous proportions that are no longer related to the module. After a phase of greater constancy to be observed in the central area, everything changes unpredictably.
The eight planes that are wholly proportional to the module form a large square when viewed all together. The square shows a slight horizontal prevalence to compensate the vertical format of the canvas. The space in this square field displays a certain degree of constancy whereas everything changes around it. With a large square visibly structured and colored within, Mondrian seeks here to present a unitary synthesis open to multiplicity; the one and the many.
With Composition B the artist seems intent on effecting interpenetration between the white rectangle unit and the large rectangles of colors in its immediate vicinity we see in Fig. 1a.
Because it is chromatically so heterogeneous, however, the large square which should suggest unity does not manifest itself with sufficient clarity and that’s why in a following canvas the square turns again into a more evident white field defined by black lines (Fig. 3):

Composition with Yellow, Red, Black. Blue and Gray, 1920, Oil on Canvas, cm. 51,5 x 61
Composition with Yellow, Red, Black, Blue and Gray develops freely and is no longer subject to any pre-established module as in Checkerboard with Light Colors and in Composition B.
The number of planes decreases in the transition from 1919 to 1920 and the composition now displays a greater degree of synthesis. There is a decrease in the number of parts but an increase in their reciprocal diversity. The sense of multiplicity expressed in primarily quantitative terms in the checkerboard composition now gives way to a sense of multiplicity expressed through difference in quality of the respective parts.
Mondrian does not see the square as a closed and pre-established geometric shape but rather the given moment in which the relationship between opposites attains a certain balance which is then lost when the different aspects again start to challenge and attain predominance over one another.

Composition with Red, Blue, Black, Yellow and Gray, 1921, Oil on Canvas, cm 35 x 39,5
Fig. 4: The square unit is stirred by an asymmetric distribution of colored planes of various size and proportions. The artist suggests the uncertain and temporary nature of our attempts to find balance and unity of opposites.
Every Neoplastic composition expresses this dialectic between the contradictory aspects and the unforeseeable flow of existence in everyday life and the human need to stabilize them and find something of greater constancy and duration. A square form keeps space constant while differences in size, proportion and color change it.
After reverting to an homogenous white field expressing unity (Fig. 3 and 4), Mondrian still endeavored in the works of 1921-22 to express both the one and the many at the same time (Fig. 5 and 6), but then ended up once again highlighting a large white square, made more dynamic and asymmetric by a variable set of colored areas (Fig. 7 and 8). The unitary/constant aspect and the manifold/variable aspect influenced one another reciprocally while remaining clearly separate and distinct.

Composition with Large Red Plane, Yellow, Black, Gray and Blue, 1921, Oil on Canvas, cm. 59,5 x 59,5 with Diagram
Everything seems subject to change in these compositions in terms of form or color. The space is in motion. More balanced syntheses are generated every so often (1, 2, 3, 4).

Composition with Yellow, Blue and Blue White, 1922, Oil on Canvas, cm. 53,3 x 55,3 with Diagram
The square appears as a constant module always changing in colors, size and proportions while preserving its function to suggest unity and multiplicity at the same time just as the waves of an ocean that are all different from one another but always made of the same water.

Composition with Blue, Yellow, Red and Gray, 1922, Oil on Canvas, cm. 34,8 x 38

Composition with Red, Yellow and Blue, 1927, Oil on Canvas, cm. 51,1 x 51,1
It is important to reassert that we use the word „square“ to describe a balanced relationship between horizontal and vertical which is in fact never a preconceived geometrical form. Mathematics have nothing to do with Neoplastic space. Every square proportion of each individual composition is different from the other according to the context: here we see a slightly more vertical square and there a square which expands horizontally.
The interaction between the one and the many goes on with new compositions.
With respect to the compositions of the early 1920-21 the lines acquire now greater autonomy and the composition becomes more dynamic. In the compositions of 1920-21 (see also Fig. 3 and 4 higher up on this page) the lines can in fact almost be seen as framing the large square that occupies most of the central area and thus inhibits their dynamic continuity. In these new compositions of the late 1920s the square instead seems to be generated by the space of the lines and to share their infinite quality.
With the lines taking on the function of expressing space that continues uninterruptedly, the artist’s gaze can concentrate on the square and a smaller number of planes. The painter uses virtually endless lines to maintain ideal contact between the finite space of the canvas and the multifarious real space of life. Balanced compositions transforms imbalances, which multiply out of all proportion in reality, into ideal equilibriums manifested on the surface of a canvas.

Composition 1 with Red and Black, 1929, Oil on Canvas, cm. 52 x 52
The two perpendicular lines running through these new compositions divide its plane into a series of open sections that expand, together with the lines, beyond the perimeter of the painting toward virtually infinite space. We see the inner sections as squares only by relating them to the perimeter of the painting. It is the sides of the canvas that determine the proportions generating the composition. This interaction between infinite space and finite space generates the relations and proportions that work together with the weight of the colors toward a dynamic balancing of the whole.

Composition II with Blue and Yellow, 1930, Oil on Canvas, cm. 50,5 x 50,5
The rectangular and square fields, large or small, are in unstable equilibrium between the infinite extension of the lines and the finite space of the canvas. These fields are defined and undefined at the same time. This interaction between definite space and indefinite makes the closed and stable square appear uncertain. Our quest for balance and unity is challenged by the unforeseeable course of life (the endless lines and the variable proportions nearing unity without ever really attain it). On observing these works, we are faced with a space that lasts and is already different a moment later.
The lines have grown in thickness and continue beyond the perimeter of the canvases. As Maurizio Calvesi points out, the canvas is “an ideal center in which the spatial event is determined in its wholeness and totality no less than in its dynamic continuity. Mondrian wrote in 1920 that the straight lines intersect and touch one another tangentially but continue uninterruptedly. The result radiates out in fact from the painting to the infinite, but the canvas exhausts the intuition of the whole within itself.” The lines hint at the immeasurable extension of physical reality the canvas is part of; a part which aim at ideally concentrating the whole in its essence.
As mentioned, we see the inner sections as squares only by relating them to the perimeter of the painting. These compositions are therefore in dynamic equilibrium between a space expanding and the same space momentarily concentrated in finite and more stable relationships.
Fig. 12 presents four areas verging to the proportions of squares (1, 2, 4) which are fully accomplished in area 2 only which however remains open and therefore subject to the expanding action of the lines. The closed area 1 appears as the only well defined square (slightly horizontal to compensates the vertical prevalences of areas 3, 5, 6) while area 5 again suggests indeterminate proportions. The parts express an intimate sense of permanence and duration while everything is nonetheless on the verge of flux and motion.
Fig. 13: Two perpendicular lines and two segments generate planes tending toward square proportions. The visibly thicker vertical segment serves as a counterweight in the lower right section to the visual weight of the yellow square in the upper left section. This composition is a clear example of how we identify as squares areas which actually extend indefinitely beyond the space of the canvas.
The message of these compositions seems to be that there is nothing more different than entities that appear to be almost the same.
Fig. 14: While the squares open up and expand in various works of this period, other compositions show a square proportion which appears in a closed form clearly defined by four sides. The two central perpendicular lines seem intent on pulling the square unit toward the upper section and the left, while the accent of color exerts a pull to the right. Unity is challenged by opposite directions. How often this happens during our daily lives.
Fig. 15: We see here a variety of squares including two in color and two in white, one large and three smaller. The large blue square and the smaller yellow one appear to contend for the space previously occupied by a large central white square whereas the black vertical segment serves to redistribute the weight and keep the whole in a state of dynamic equilibrium.
Fig. 16 consists of seven different areas; some verge to proportions of squares (1, 2, 3) while others show a prevalence of one direction over the opposite. Square 2 remains open at the bottom and to the left while square 3 opens toward the top and to the right. The red and the blue planes extend beyond the canvas as well. Area 1 is the only fully accomplished square closed on four sides.
As mentioned the artist seeks in these works to open and expand the square while maintaining its visibility at the same time. The concept of space here is still essentially the one that inspired his work from the very beginning: opening up to variety and mutability on the one hand while tending to concentrate on the other and thereby generating an ideal, more constant synthesis which then re-opens to variety and mutability.
The space of these compositions is markedly asymmetric but everything is kept in perfect equilibrium. It does the mind good to think that asymmetry and diversity can be resolved in a harmonious space. If only this could be achieved more often in social life.
The play of equilibrium regards not only form but also very subtle vibrations of color. The planes appear to have been painted there and then, thus suggesting intuition more than cool elaboration. The fields of red are splendidly rendered, as indeed are those of white, which have none of the flatness unfortunately seen in standard reproductions. There are extremely subtle variations of every primary color, as there are of every shade of gray. As Jaffé wrote: “The painter let himself be guided by his feeling for color and rhythm, and he made alterations and corrections as he worked; over paintings to change the color of some of the areas can still be detected. The skilled treatment and masterly balance of the canvases are the result not of a theory but of a long experience as a painter.”
Throughout the 1920’s Mondrian worked on a series of compositions developed on a lozenge format.
The choice of this format gives greater breadth to the composition. It makes it possible to use lines of various lengths.
New relations of tension are established between the orthogonal planes and the diagonal sides of the painting.
The four corners of the lozenge generate a centrifugal energy and seem to expand the plane of the canvas along its two median axes.
The lozenge therefore already seems in itself a way to make the equivalence of opposites, i.e. the square, more dynamic.
On observing the four lozenges we note how a closed area nearing the proportions of a square (first lozenge) opens up (second and third) while in the fourth one a closed square re-appears which consists of lines which assume variable thickness. On the one hand an open square area extends with the lines toward a virtually infinite space (the finite opens up to the infinite; the one opens up to the many) and on the other hand a renewed closed square is made of a relative multiplicity through lines varying in thickness. In both cases, the one interacts with the many. Once again, Mondrian seeks in these works to open and expand the square while maintaining its visibility at the same time.
We shall now examine Lozenge with Yellow Lines which constitute a synthesis of all previous compositions of this type.
The square in this composition has the same proportions as the canvas. The four lines show a progressive increase in thickness as we move clockwise from the vertical on the right. The increase in the thickness of the lines can be seen as the vertical incorporating a slight horizontal expansion or conversely as the horizontal growing thicker in response to barely perceptible vertical pressure. For a fraction of a second, the space of the lines is simultaneously vertical and horizontal, i.e. a synthesis of the opposite directions. From this point of view the lines seem to transform into embryonic planes. We actually talk about a square that we do not really see in full since the lines never meet inside the canvas. In point of fact each line could well continue on its own towards infinite space without being really concerned to relate with the opposite lines as to give birth to a square proportion. Our mind translates infinite space (the uninterrupted lines) into a presumed finite space (a square form); four separate and different elements (their variable thickness) hint at a probable square unit which is, however, beyond our field of vision.
The more important innovation is obviously the fact that, for the first time, the lines are no longer black but yellow. The field is uniformly white and the yellow shape almost appears to be born out of the white rather than in opposition to it, as in the case of the black.

Yellow is an intermediate value between black and white, sufficiently dark to be differentiated from white but, at the same time, not so radically opposite as black. The opposite values now seem communicate and achieve unitary expression in terms both of form and of color, with horizontal and vertical simultaneously present for an instant in every line and the synthesis of black and white in an intermediate color, which yellow appears to constitute in this case. On observing this square and contemplating the differing thickness of the lines, we are faced with a unity undergoing transformation from one side to the other; a synthesis that already appears comparatively manifold in itself. We perceive a unity that tends to become rather than to be. It endures but changes at the same time; a square that is open, dynamic, asymmetric, and entirely expressed by color.
This composition goes to the heart of the problem: to show the manifold in unitary form; to open up unity, i.e. the postulate of consciousness, to the changing aspect of the natural universe and existence in time but without losing sight of it. Once again we recall the fundamental issue: The one and the many appear as antithetical realities in the human dimension; in actual fact, they are the same thing.
The dialectic between unity and multiplicity continued throughout the 1920s and early 1930s. The single white square field (1920) took on color, underwent duplication and opened up on one or two sides (1930). A closed square developed out of the dynamic continuity of the lines around 1931: sometimes more horizontal, sometimes more vertical; sometimes larger, sometimes smaller; sometimes blue, sometimes yellow. The single square of 1920 gradually gave way to a variety of probable square forms. Unity and multiplicity tended to interpenetrate.
In actual fact, the square opened up and interpenetrated with the variety of forms and colors in the rectangular canvases while seeking in the lozenge compositions to absorb that variety with no extensive change to itself. In the first case, the square opens up in the direction of multiplicity; in the second, the square absorbs multiplicity while remaining substantially one:
In this phase Mondrian is like a composer who gradually reduces the orchestra to a solo instrument, an almost imperceptible sound that can still be varied in an effort to express the whole. In a white field crossed by four black lines, the thickness of a line can also serve in a space moving toward ever-greater synthesis to calibrate the weights and influence the overall economy of the composition.
These lozenge compositions constitute the moment of greatest correspondence between the one and the many.
With the canvases of the late 1920’s and above all this lozenge of 1933, the artist appears to have given material expression to an idea that had guided him, canvas after canvas, for roughly twenty years of work, namely to express the multiple in unitary form and endow it with the stability required by consciousness without, however, causing it to atrophy in overly rigid and constant geometric forms. The artist felt for a moment that he had achieved his objective with a square undergoing transformation while remaining relatively stable.
Nonetheless, if we compare Lozenge with Yellow Lines with the previous works and in particular with those produced up to 1920:
it appears immediately obvious that by 1933 the multiple aspect had been considerably reduced almost to the point of elimination. Around 1930 Mondrian painted in black and white or with one or two colors inside predominantly white fields. In the span of a decade, the manifold space (1912 – 1919) appears to have been completely absorbed by the square, which was used during the 1920’s and early 1930’s in an attempt to reformulate in conceptual synthesis a space that is in reality far more structured and complex. The square we see in Lozenge with Yellow Lines is a symbolic representation that does not suggest the variety of the real world. In 1933 the space of external reality had undergone marked internalization in the far more condensed forms of thought; the physical seemed to be expressed in excessively mental terms. The painter was soon to realize that his canvases did not convey a sense of the variety perceived by the eye in nature or urban space, the rich and multiform aspect of color previously captured with his dunes and trees, his Cubist works, and his checkerboard compositions. While Lozenge with Yellow Lines can therefore be regarded as a point of arrival, at the same time, as in other moments of Mondrian’s artistic development, the work also represents a new point of departure.
As Michel Seuphor puts it in his beautiful biography of Mondrian: “Sometimes he thinks he has found it. So he stops, observes the work, and says: It’s done. But the clock of his life keeps on ticking and is already driving him forward. He soon realizes that nothing is done and everything has to start all over again.”