Smalltalk and Self are two paradigmatic examples of class-based and prototype-based late-bound object-oriented programming, respectively. Many of their similarities and differences can be grounded in how they bind message names to concrete values, but the details can be subtle and are not available in a concise form. The Id object model abstracts over specific binding semantics, even permitting the flexibility of late-bound message sending \textit{as part} of binding semantics, so it is worth using as a common basis on which to compare them. In this paper, we present the method-binding semantics of Smalltalk and Self as different ``special cases'' within the Id object model.