Personal identity is an elusive notion. Some contemporary thinkers question whether it has any substantive reality or even whether it is important. This has potentially alarming implications for our belief in ourselves as responsible agents. Many of the difficulties of pinning down personal identity result from confusing different aspects of a very complex notion. Identity has subjective dimensions: my sense of who and what I am at any given time; and my sense of being the same individual over a period of time. These dimensions in turn have many elements. There are also the external aspects of identity: those characteristics by which, and with which, I am identified and classified by others and which count as objective criteria for my remaining the same person. Since John Locke, many philosophers have sought the basis of personal identity in the mind: in our psychological continuity over time, mediated by memory. More recently, some philosophers have emphasised the role played by the physical continuity of the body. While each approach captures some aspects of identity, neither gets to the heart of matter. What is more, continuity accounts focus on sameness of identity over time and on objective or external criteria for identity rather than the immediate, unassailable moment-by-moment intuition of identity. We cannot, however, understand what it is that confers sameness of identity over time unless we can understand what gives us a sense of identity at a particular time. I will argue that the primary location of identity is a moment-to-moment sense of being myself, which is quasi-tautologous, unassailable and underivable. This is rooted in what I have called The Existential Intuition `That I am this.. .’ . `This’, in the first instance, is my body. The self-apprehension of the human body, which is neither purely psychological nor purely corporeal, is the common point of origin of the various subjective and objective dimensions of personal identity and of the various senses of what I am now and of what is the same in me over time. The scope of `this’ expands beyond the body as the individual undergoes cognitive development and enters a world of possibility and fact, extending into past and future. The Existential Intuition is unique to humans: no other organism apprehends itself, that it is, to the same degree. It is the basis of human freedom and moral responsibility.