I will argue that Locke believed that if you remain the same person, there are various entities contained in my body and soul composite that do not remain the same over time, or that we can conceive them changing. These entities are matter, organism (human), person (rational consciousness and memory), and the soul (immaterial thinking substance). This is a intuitive interpretation that creates many questions and problems. I will evaluate Locke's view by explaining what is and what forms personal identity, and then explaining how these changes do conceivably occur while a human remains the same person.
Locke believed that the identity of a person could be assigned to the consciousness. He thought that a person would remain the same as long as their consciousness continues to be the same over the course of their life: “Consciousness always accompanies thinking, and makes everyone to be what he calls ‘self’ and thereby distinguishes himself from all other thinking things; in this alone consists personal identity, i.e. the sameness of a rational being; and as far as this consciousness can be extended backwards to any past action or thought, so far reaches the identity of that person” (Essay II.xxvii.9). Locke believes that your body and your personality do not determine your identity. Instead, you can know that a person is the same person as long as their consciousness continues to be the same over the course of their life.
Locke believed that the identity of a person has the sameness of the consciousness: “What makes a man be himself to himself is sameness of consciousness, so personal identity depends entirely on that—whether the consciousness is tied to one substance throughout or rather is continued in a series of different substances” (Essay II.xxvii.10). This means that the identity is made from memory and other facts about the person. An example of this is that someone existing today is the same as they were yesterday because their consciousness continued to be the same as it was the previous day. This means they are the same person because they remembered their actions and experiences. So if those memories and facts do not exist anymore due to an accident of some sort, then that person no longer has the same identity. An example of this would be someone waking up one day and not remembering anything about their life, this would mean that they now have a new identity.
Locke explains that these changes do conceivably occur while a human remains the same person. Let us say there is a cluster of matter in a human. So a person's face has all this matter forming it. If you move around the cluster, but it has all the same fragments in the cluster as it did previously, then it would remain to have the same identity. However, if you remove a single fragment of that matter out of the cluster, then it becomes a different identity. It can no longer be considered as having the same identity if that fragment is removed. Being a human is when you have...