This thesis examines the life and New Zealand works of the Lithuanian born artist, Rudolf Gopas (1913 - 1983), Gopas has been credited with introducing German Expressionism into New Zealand and with being the father of expressionism in modern New Zealand art. At the same time he has been accused of failing to become a New Zealand artist. These claims are examined, when it becomes apparent that while it is questionable that he introduced German Expressionism into the country he did, for a time, paint in a German Expressionist style and can be viewed as the father of modern New Zealand expressionism. This was a brief interlude however, and to characterise him as a German Expressionist painter is inadequate. While he did accommodate to New Zealand, he is shown to have been conscious of the international character of twentieth century art. In the thesis the nature of German Expressionism is considered and related to the early experience of the artist. His biographical details are presented for a better understanding of his later New Zealand painting. This is followed by a detailed consideration of the New Zealand works, which are studied in relation to his reception for the light this sheds on his art. When this is done it becomes apparent that his works fall into three periods; an early period of adjustment and re-establishment as an artist, when the works were largely naturalistic; a middle one when German Expressionist influences predominated; and a late one when the cosmological works were produced, which is shown to have been his most creative and significant. Throughout his professional career Gopas was subjected to a variety of changing influences and these are shown to have been assimilated and integrated with his wide ranging interests into a new form of expression. In the preparation of this thesis, 169 works and three individual volumes of Nature Speaks were examined, nineteen interviews were conducted with collectors, associates and relations, as well as extensive correspondence entered into with various people.