In this chapter I will consider two puzzles: How do humans in general form a cohesive consistent sense of identity despite constant change? How does each person form a sense of uniqueness—of individuality? I will distinguish between three terms:

A core sense of self which is fundamental to both the formation of identity and uniqueness,

Identity which involves names and recognizable characteristics—John is 12 and the fastest runner on the school team. Mary is 30, unmarried and a serious determined biologist,

Sensibility which emerges as a characteristic, capacity or preferences of particular emotional significance to the individual. John is uncomfortable when he is praised. His mother knows it and avoids embarrassing him; his father teases him about it. Mary deeply responds to nature with great exhilaration. Traveling to beautiful places is central to her enjoyment of life.