Today's blockchain is like a music box: the melody (the rules of the game) is embedded in the mechanism, and to change it you have to take the whole thing apart. Every time developers want to change an application's logic, they have to perform a fork, splitting the network into two branches that then compete with each other. It's as if installing a new app on your phone required rebuilding the operating system from scratch each time.

Enso offers a different path. Instead of hardwiring logic into the node's code, it stores logic in the blockchain's state itself, right next to the data. The system state is a collection of objects called actors. Each actor has an address, code, and its own storage. When a user sends a transaction, it becomes a message in a shared queue. The node processes messages one by one and delivers them to the recipient actors. Those actors, in turn, can spawn new messages. This continues until the queue is empty.

This idea isn't new: the actor model was conceived back in 1973. But Enso pushes it to the limit of simplicity. It removes parallelism and personal mailboxes, leaving a single global queue. Only two types of entities remain: actors and messages. Kernel actors are created at startup and define the rules, while user-defined actors are created from templates and store data.

The practical benefits are immediately apparent. Developers no longer need to organize forks for routine logic updates. Users experience fewer network splits and more predictable protocol evolution. Forks remain only for rare changes to the virtual machine or consensus.

A blockchain that can store logic as data is reminiscent of the shift from plugboard computers to stored-program machines. If the idea catches on, blockchains could become like operating systems where applications can be updated without reinstalling the kernel. The music box turns into a piano on which you can play any melody without taking the instrument apart.