 His brother Johannes (1585-1631) was also a renowned ecclesiastical personality besides being an outstanding Cologne historian who began to put together some valuable historical sources about the history of the archdiocese of Cologne in his bid to write a comprehensive book but could not complete as he met with a premature death.But his brother Aegidius promised to complete his work when he was on the deathbed and accordingly Aegidius left his job and began to concentrate only on the work that his departed brother began.After spending almost 15 years ”day in day out”, he put together a 30-volume historic work from original sources.