Abstract

I argue that each object has many essences. A property E is an essence of object x if and only if E is essential to x and in every possible world everything distinct from x has the complement of E essentially. I then elaborate on the nature of essences and examine the relationship between essences and proper names. My view is that John Stuart Mill was mistaken in his belief that proper names do not express properties. In fact, proper names express essences and I make use of this fact in addressing the famous problem of Hesperus and Phosphorus.