"...things such as functions and methods look essentially the same, but they derive from very different ideas. A method reflects a behavior expected in the domain, and a function reflects a unit of execution in the machine. A message and a function call might be identical, in syntax and in how they are implemented inside a machine. But who sends the message to whom, how that message is interpreted, and what kind of code will be necessary to respond will be quite different." — David West, "Object Thinking"