The article discusses the concept of programmable ink, which allows users to create dynamic and interactive sketches. The authors draw inspiration from the success of spreadsheets and aim to create a tool that combines the flexibility of pen and paper with the computational power of digital media. They explore the potential use cases and research questions surrounding this idea, including the design of a programming model and interface. The goal is to create a tool that enables users to define new computational behaviors and interact with their sketches in a more meaningful way.