Tobias was a minimalist sculptor and abstract painter. These pieces are fine examples of abstraction. Both are untitled. The colorful piece is from 1968 and the black and white one from somewhere between 1958 and 1961.
He was a Marxist and he flew bombing raids during the war--the view from his perch in the B-16 apparently influenced the sculptural works he created in later years. The Independent ran this obituary for him in 1999.