  This is further developed in Regius 1654, in which he argues that the concepts of extension and thinking are not incompatible and, “accordingly, they [the attributes] may both be present in the same simple subject” (337). This anticipates the question (and the implied answer) that was discussed by Locke, in the Essay IV, iii, 6, whether God may have superadded thought to a material substance. In the version proposed by Regius, there are no reasons why it would be impossible for a material entity to have the property of thinking because, although thinking and extension have nothing in common, they are not incompatible.