Alan Kay has said that when he was designing Smalltalk he thought about the idea of recursive design. The idea of recursive design is that the structure of the part mirrors the structure of the larger unit, rather the way that fractals work or baroccoli grows. That is, rather than think of a computer as being composed of parts that each have less power than the original, what if we think of a computer as being made up of lots of little processing engines.
Each of these processing parts, called objects, can be thought of as a computer-in-the-small. They will have similar computational power as the computer as a whole, and the processing will proceed by these things acting together.