Although not a particularly well-known figure in the history of philosophy, the importance of Jackson's work as representative of some of the major controversies in the first half of the 18th century should not be overlooked. With the dualism of matter and spirit firmly established, many thinkers struggled for an explanation of mind/body interaction. In "A Dissertation on Matter and Spirit" Jackson attacks the argument that God is the only genuine cause of the influence of matter on mind, and is significantly swayed by Locke's belief in thinking matter. However, as might be expected of a clergyman, he maintains that matter and spirit are essentially different, but continually qualifies this as based only on conjecture. Clearly examining the key elements involved, this pamphlet is a significant contribution to the materialism-immaterialism debate.