 Having set forth the general machinery of how simple and complex ideas of substances, modes, relations, and so forth are derived from sensation and reflection, Locke also explains how a variety of particular kinds of ideas, such as the ideas of solidity, number, space, time, power, identity, and moral relations arise from sensation and reflection. Several of these are of particular interest. Locke’s chapter on power gives rise to a discussion of free will and voluntary action (see the entry on  Locke on freedom).  Locke also made a number of interesting claims in the philosophy of mind. He suggested, for example, that for all we know, God could as easily add the powers of perception and thought to matter organized in the right way as he could add those powers to an immaterial substance which would then be joined to matter organized in the right way. His account of personal identity in II. xxvii was revolutionary. (See the entry on  Locke on personal identity).  Both of these topics and related ones are treated in the supplementary document:  Some Interesting Issues in Locke’s Philosophy of Mind 