According to the Encyclopaedia Britannica, John Locke defined consciousness as “the perception of what passes in a man’s own mind.” I suppose that it is true that Locke said so, although I cannot check it, for there is no reference added to the quotation, which actually is to be expected in a work of that standing. Anyway, the passage is not from the famous chapter XXVII “Of Identity and Diversity” in Locke’s An Essay concerning Human Understanding (first published in 1689, but this chapter was added in 1694). Here Locke develops the idea of personal identity and links it to the idea of consciousness. For instance, in §19 Locke says that “personal Identity consists, not in the Identity of Substance, but ... in the Identity of consciousness ...” The idea of consciousness was not an invention of Locke. Already Plato and Aristotle formulated theories on consciousness and the English word “consciousness” existed already more than a century before Locke wrote his Essay. However, just as we can call Descartes the father of epistemology because he first systematized scientific methodology (see my blog last week), we can call Locke the father of consciousness theories because he first gave the concept a full place in philosophy and science.As my quotation from the chapter on identity and diversity in the Essay illustrates, for Locke consciousness and substance – so mind and body, as we would say now – were two different things. In this respect Locke’s approach of consciousness was Cartesian. So for Locke it was basically possible that “the soul of a prince, carrying with it the consciousness of the prince’s past life, enter and inform the body of a cobbler” (§15 in chapter XXVII of the Essay), for the bodily characteristics of the prince were not part of his personality. We still find this separation between mind (or consciousness) and body in the modern discussion on personal identity, from Bernard Williams in “The self and the future” (Philosophical Review 79/2: 161-180) till Derek Parsons in Reasons and Persons (1984) and thereafter, and the so-called psychological-continuity theories of personal identity still form the mainstream view on personal identity, despite alternative views of, for instance, John Olson (The human animal (1997)) and myself (see http://www.bijdeweg.nl/PersonalIdentity.htm). Only now it becomes more and more accepted that substance and consciousness in man, so mind and body, are fully integrated. For some this means that man is nothing but a body or that man is a kind of biological machine, or how they see it; anyway that man is a completely material being and that the mind is a kind of epiphenomenal effect emerging from the human matter. Others, like me, prefer a dual aspect view on man, which says that man can be considered in different ways: as a biological body or as a conscious and thinking mind, although in the end man is both together. I think that this view makes it also easier to understand how in a certain sense man can survive his or her material dead. With this remark I do not mean that man can survive in any religious sense, for example as a soul, but the idea that mind as one of the two aspects of man makes it possible to understand how culture can survive the bearers of a certain culture; how ideas can remain to exist and have influence long after the thinker of these same ideas who has written them down in books or on the Internet has passed away. But maybe this is not as anti-Lockean as it seems on the face of it, for didn’t Locke say in the §15 just quoted that “The body, as well as the soul, goes to the making of a man” and that the cobbler who would receive the soul of a prince still “would be the same cobbler to every one besides himself”?