[2][3] Later credited as the "big bang" [4] of the movement, the work not only attracted the attention of fellow Tama students but also Lee Ufan, who was senior to Sekine and in search of a theoretical framework for new art.

This work led to an intense intellectual exchange between Sekine and Lee,[5] involving other Tama students, that served as a foundational theory of Mono-ha, that combined Sekine’s principle of “not making” (tsukuranai koto) [6] and Lee’s idea of “the world as-it-is” (arugamama no sekai), [7] setting a stage for themselves and their peers to embark on a full-fledged exploration of mono (things), which became the name for their movement.

[9] By 1970, Sekine established himself as a young but rising figure of contemporary art, being invited, along with Shusaku Arakawa, to exhibit in the Japanese pavilion at the Venice Biennale in 1970, by the critic Yoshiaki Tōno.

Despite these attentions, the artist departed the Mono-ha practice and established Kankyō Bijutsu Kenkyūjo (Environment Art Studio) in 1973 to focus primarily on public sculpture.

[12] Takamatsu’s illusionistic paintings and sculpture were central to the development of the Tokyo art scene at that time, as well as his performances and actions that belong to the anti-art trend (Yamanote Line Incident, and other events of the group Hi-Red Center, which he co-founded).

[12] The major turning point in Sekine’s career came in October 1968, when he created the work Phase: Mother Earth in Kobe’s Suma Rikyu Park for the First Open Air Contemporary Sculpture Exhibition (第一回野外彫刻展).

Eventually, Sekine consulted a geology laboratory at the University of Tokyo, which advised him to alternate layers of earth with cement, before treading them down firmly.

Sekine recently likened it to an ‘accident’ that hit him (and the two other Mono-ha artists who assisted him, Yoshida and Koshimizu Susumu) over the course of a week, though at the time he was unable to put into words the impact he felt.

Lee Ufan shed a light on the ‘accident’ that struck Sekine, Koshimizu and Yoshida :Since time immemorial, the world is always completely fulfilled ‘as-it-is’, (aragamama).

Of this piece, curator Simon Groom wrote:[4] Simply presented in its natural state, the huge mass of clay seems to exist in a constant state of tension between our awareness of its overwhelmingly physical presence and our conscious desire to form it, whether mentally through the profusion of possible forms it may suggest, or physically, drawn as we are to the tactile nature of the material in its infinite malleability.Phase of Nothingness—Water (1969) (空相：水) consisted of two containers of water, one a 110 cm high cylinder and the other a 30 cm high rectangular box.

Yoshiaki Tono, commissioner of the Japan Pavilion wrote : SEKINE has said the artist today does not create anything; he merely brushes off the dust from things, and shows them as they are, not as our prejudices see them.

He is scheduled to participate in the International Symposium in the Venice Biennal, at which he is expected to construct a work similar to the one he exhibited at the Hakone Open-Air Museum this last year.

[24] His success at the Venice Biennale led to him being offered a number of solo shows in Europe, including a traveling exhibition featuring a major body of sculptural work, Phase of Nothingness—Black (1978–79)(空相—黒).

The approximately 50 sculptures range from rough, clod-like forms that lie low on the floor to highly polished, geometric shapes that stand tall like totems.

When Sekine installed these works, he considered their placement to be a “topological scene” governed by aesthetic principles similar to those found in Zen rock gardens—namely, asymmetric arrangements of disparate elements that combine to represent a broader landscape of seas, islands, and mountains.

Sekine’s work has received renewed attention in the United States following his inclusion in Requiem for the Sun: The Art of Mono-ha, at Blum & Poe, Los Angeles, in February 2012.