On Kawara, the Japan-born conceptual artist who made his home in New York City for the past 50 years, has died. He was 81. A representative for David Zwirner, his gallery, confirmed the news of his passing to Gallerist. A note has also been posted on its website.

For the better part of a century, Kawara investigated the nature of time and played with the idea of identity in the face of death. He refused all interviews and declined to have his picture taken.

For his “Today” series, which he began in 1966 and produced throughout his career, he meticulously painted that day’s date on canvas. He worked without stencils and used the date-notation system for the country he happened to be working in. These works were generally paired with newspapers from the same day.

His work is currently on long-term view at Dia:Beacon, and he will be the subject of a massive retrospective at the Guggenheim, “On Kawara—Silence,” which opens Feb. 8, 2015.

One of his other best-known series is “I Am Still Alive,” which consists of telegrams that he sent to various friends and acquaintances, each of which proclaims, “I am still alive.”