John Locke, as an empiricist, holds very different views from Plato and Descartes. How does Locke defend empiricism?

” This may shew us wherein personal identity consists, not in the Identity of Substance, but, as I have said, in the Identity of consciousness.” (John Locke, p. 312)

John Locke, as an empiricist, holds very different views from Plato and Descartes. How does Locke defend empiricism? What is the problem of personal identity? What are Locke’s views on this matter? Why does he distinguish between masses of matter, living things and persons? How, in detail, do Locke’s views differ from Plato and Descartes? What do you make of Locke’s arguments?