Tag Archives: interesting reads


man muss immer umkehren – Carl Gustav Jacob Jacobi(loosely translated – Invert, always, invert) Today, we will look at one of my favourite mental models called – The Inversion principle. Mental models are a set of simple, abstract but useful principles that help us make sense of the world

Source: Invert, always, invert


I sold, on average, 541 copies of both books per month prior to March. In the months of March and April, that average shot up to 32,450, or a 60x increase in cumulative sales. I was able to give away almost 65,000 copies of my books—and not only that, they are full LeanPub copies, entitling the new readers to free updates to the books, forever.What amazed me most, though, was that in contrast to the maxim No good deed goes unpunished, paid book sales almost quadrupled!Here’s a graph of royalties per month for Ansible for DevOps (the Ansible for Kubernetes graph doesn’t have as much meaningful data to spot trends):

Source: I gave away my books for free, and sales increased 4x | Jeff Geerling