Significant to the history of science, Sir John Leslie’s election to the Chair of Mathematics in 1805 provoked Enlightenment debate over how much power the Church of Scotland should have over the science departments at Scottish universities. Until the mid-nineteenth century, the Lord provost, magistrates and the town council elected vacant Chair positions at Scottish universities. Leslie’s case resulted in a trail against his religious beliefs, moral principles, reputation and career before the General Assembly of the Church because parties in each of the election groups debated over whether Leslie was the right candidate. Caused by Note 16 attached to his Inquiry on the Nature an Propagation of Heat (1805) where he credited David Hume (1711 – 1776) for his theory of causation, which was believed to have disregarded God’s holy power. Leslie was found not guilty and was Chair of Mathematics for fourteen years. This was an incredible victory, for Leslie became Scotland’s first non-ordained professor, establishing a precedent that weakened the influence of the Church. Although it did not immediately end the election process, it did stop the use of its power over the future appointments in the Faculty of Arts at Edinburgh University.