Burnet's best known work is his Telluris Theoria Sacra, or Sacred Theory of the Earth. The first part was published in 1681 in Latin, and in 1684 in English translation; the second part appeared in 1689. It was a speculative cosmogony, in which Burnet suggested a hollow earth with most of the water inside until Noah's Flood, at which time mountains and oceans appeared. He calculated the amount of water on Earth's surface, stating there was not enough to account for the Flood. Burnet was to some extent influenced by Descartes who had written on the creation of the earth in Principia philosophiae, and was criticised on those grounds by Roger North. The heterodox views of Isaac La Peyrère included the idea that the Flood was not universal; Burnet's theory was at least in part intended to answer him on that point. Burnet's system had its novel features, as well as those such as the four classical elements that were very traditional: an initially ovoid Earth, a Paradise before the Flood that was always in the spring season, and rivers flowing from the poles to the Equator. Herbert Croft published criticism of the book in 1685, in particular accusing Burnet of following the Second Epistle of Peter rather than the Book of Genesis. During the 1690s John Beaumont and Johann Caspar Eisenschmidt picked up on Burnet's ideas. They engendered a great deal of controversy at the time, and Burnet defended himself against selected critics, John Keill and Erasmus Warren. Isaac Newton was an admirer of Burnet's theological approach to geological processes. Newton even wrote to Burnet, suggesting the possibility that when God created the Earth, the days were longer. However, Burnet did not find this explanation scientific enough. Lengthening the days would require an intervention on God's part. Burnet tightly held the belief that God created the world and all its processes perfectly from the start. He wrote:
We think him a better Artist that makes a Clock that strikes regularly at every hour from the Springs and Wheels which he puts into the work, than he that hath so made his Clock that he must put his finger to it every hour to make it strike.
''The Ancient Doctrine Concerning the Origin of Things''
Some of the views expressed in this work, also known as Archaeologiae Philosophicae sive Doctrina Antiqua de Rerum Originibus, were so unacceptable to contemporary theologians that he had to resign his post at Court. In this he considered whether The Fall of Man was a symbolic event rather than literal history.
Burnet's treatise De Statu Mortuorum et Resurgentium was published posthumously in 1720. In Edward Gibbon's The History of the Decline and Fall of the Roman Empire III p. 99 Gibbon made reference to Burnet's De Statu Mortuorum et Resurgentium noting that Burnet "exposes the inconveniences which must arise", if souls "possess a more active and sensible existence." Thomas Newton, Bishop of Bristol and Dean of St. Paul's, criticised Gibbon and claimed that Burnet's views were exactly the opposite.
