The 1950s saw two turning points in Zao's career. The first was his development towards the oracle bone series. This took place in 1954. Zao was able to simplify natural forms with their contours, informed by his understanding of the use of 'line' and its artistic possibilities. The 'oracle bone series' illustrates his belief that "painting should enable people to look at things through a different lens... hence I have to create a common language which is not bounded by themes or subjects." As the outline of forms, lines are not dependent on forms, they themselves are in fact an abstract portrayal of forms. Zao was further influenced by abstract expressionism when he visited New York in 1957, and his works became even more liberated and unrestrained upon his return to Paris. Hence during 1958 and 1959 Zao produced a few works with fine lines as the main theme. These paintings do not have strong metaphorical text symbols, and the lines have not developed into the thicker and bolder lines of his works in late 1959. Untitled (Lot 10), painted during 1958-1959, demonstrates this turning point of Zao's career, providing evidence of the transformation from text symbols to delicate cursive writing. Exhibited at the 1960 Venice Biennale, it is an important piece of art history.
Lines, one of the basic elements of art, are the most refined, recapitulated language of traditional Chinese art. Paintings, calligraphy, architecture, dance are all demonstrated through lines, not only in outlining the form and structure of an object, but also as a channel through which the artist can communicate his personal feelings to his viewers. Owing to the special structuring of Chinese characters, calligraphy is written in a certain order and way. This gives rise to the unique, dynamic concept of shi (power) - shu shi (word power) and bi shi (brush power) - which is not only about the spatial elegance of the character, but also the charm of the timing and order of the strokes.
On a golden-bronze background that has been weathered by age, Zao's brushstrokes carry his emotions in their movements. His flexible wrist and skilful techniques, drawing overlapping lines of black, brown and white ink, convey action through the direction and speed of the lines. The lines are soft and fluffy, resembling the swirling ribbons in a Dunhuang Dance, looking like the cursive strokes in Chinese calligraphy, while also comparable with the paintings drawn with the spontaneous movements of US abstract expressionism. The 'action' beneath the lines is possible due to Zao's solid foundation in Chinese calligraphy since childhood. Zao is also very familiar with Western painting media after almost 20 years of Western training. He is capable of using rich and diluted paints to effectively convey his emotions - and at the instant of laying his strokes, the almost undetectable changes between fluidity and dryness act as metaphor for the passage of time and space.