> He presumably had previous experience with operating other GUI programs, and experience with standard computer concepts like programs and files. The big benef

> He presumably had previous experience with operating other GUI programs, and experience with standard computer concepts like programs and files. The big benefit here is that a lot of GUI paradigms are shared between very different kinds of programs, so something that would've been explained in text in a bound manual in the past gets covered very early on, either through experimentation, or someone explaining it. Exactly! Just like reading documentation takes a bunch of knowledge as granted that most (but not all!) of the population possesses (reading, understanding diagrams, graphs, step by step assembly directions, etc.) You've put your finger on the wonderful thing that computer interaction has given us over the past decade or two - a shared visual/interactive language that, while far from perfect, lets the average teenager pick up Audacity and be productive with it within seconds.