Robert Greville died at Lichfield on 2 March 1643. He was the adopted heir of his cousin, Fulke Greville, first Lord Brooke, who took responsibility for his education. He did not attend university, but he did travel abroad. He succeeded to the title Lord Brooke in 1628. He took an active part in contemporary politics as a staunch supporter of Parliament against the king both before and during the English civil war. He served as a Parliamentary general, and was killed in a skirmish in 1643. His opponents regarded him as obstinate, but his allies, among them John Milton, saw him as a staunch proponent of religious toleration. Greville was apparently moved to write his one philosophical work, The Nature of Truth (1640), out of a desire to comprehend some apocalyptic passages of the New Testament. He does not comment on these in his discussion, but presents his treatise as a ‘Prodromus’ to a future treatise on prophetic truth. In the course of his argument he draws on Platonic writers (Dionysius the Areopagite, Plato, Ficino), rejecting scholastics. The book shows that he was aware of the writings of Bacon and Comenius, and accepted the new science of Copernicus and Kepler. His Puritan sympathies are also evident, from his references to William Twisse, Samuel Rutherford, Thomas Goodwin and William Ames, even though he does not always agree with their views on his subject. Greville argues that truth, including moral truth, is an unknown mystery, founded in God. It resides in the understanding, which is a ray or an emanation from divine nature. The understanding is not a faculty but truth in its essence. Since Greville conceives of being as ‘light communicating’, it is by the light of truth residing in man that human beings participate in the divine. Reason too is an inward light, which distinguishes men from beasts. Knowledge is, as for Plato, reminiscence. The soul, understanding, habits of mind, faith and reason are all one, differing in degree, not in nature. The central insight to be gained is that all things are a manifestation of unity deriving from God. God is the fountain of all being, whence emanates the first created cause. As a consequence of this, all things are good, so the good of each of us is the good of all. Error is the result of ignorance, especially on account of the unreliability of the senses. In spite of Brooke's assertion that the first cause emanates from God, he asserts that knowledge of causes and of existence is uncertain; he acknowledges the problem of scepticism, but does not propose a solution.
From The Continuum Encyclopedia of British Philosophy in Oxford Reference.