Piet Mondrian (1872–1944) began his journey painting trees and landscapes; but over decades he filtered out, step by step, every descriptive detail. First he reduced a tree to the rhythm of horizontal and vertical lines, then purified even those lines. By the 1920s the point he reached was radical: no curve, no diagonal, no shadow, no recognisable object. Only black vertical lines on a white ground and the three primary colours — red, yellow, blue — filling some of the rectangles those lines form.

Mondrian called this style "Neoplasticism" (New Plastic); it was the core of De Stijl ("The Style"), the movement formed by Dutch artists. His aim was not merely formal. Influenced in part by theosophy, Mondrian believed that beneath the transient chaos of the visible world lay a universal, unchanging balance. The opposition of horizontal and vertical, of colour and colourlessness, of fullness and void sought this balance — the painting aimed not at the eye but at the mind and spirit's search for order.

Looked at carefully, these compositions are not "simple" at all: the thickness of the lines, the proportions of the rectangles, where and how large a colour is placed are decisions to the millimetre; Mondrian would seek the balance of a painting for months, re-taping the bands again and again. Asymmetrical yet balanced — not static but a tense equilibrium.

Where Malevich's Black Square reset abstraction to zero, Mondrian rebuilt it as a language of order. His influence was not confined to painting: from Bauhaus design to modern architecture, from typography to fashion and graphic design, he shaped the visual language of the twentieth century. Even the grid layout of a web page today carries the trace of his logic.