John Lighton Synge was arguably the greatest Irish mathematician and theoretical physicist since Sir William Rowan Hamilton(1806–65). He was a prolific researcher of great originality and versatility, and a writer of striking lucidity and ‘clarity of expression'. He made outstanding contributions to a vast range of subjects, and particularly to Einstein's theory of relativity. His approach to relativity, and theoretical physics in general, is characterized by his extraordinary geometrical insight. In addition tobringing clarity and new insights to relativity, his geometrical approach profoundly influenced the development of the subject since the 1960s. His crusade in his long academic career was ‘to make space–time a real workshop for physicists, and not a museum visited occasionally with a feeling of awe‘ (31)*.