Technology is often a crucial input to innovation, but so are knowledge and ideas. Indeed, technological change emerges out of ideas and, as we will see, knowledge stands in an interesting relationship to the generation of the novel ideas that you could say are essential raw materials for innovation. First, Galenson’s work provides some nuance to the nature of ideas and of knowledge, suggesting that knowledge can be both a prerequisite for and an impediment to the development of ideas, depending crucially on what kind of ideas we are dealing with. Then, the papers by Ward and Shane present two contrasting views of how knowledge can shape imagination, highlighting how one’s prior knowledge might overstructure, enable, or narrowly focus ideation. Finally, Jones’ paper zooms out to the macro level, inviting us to think about why it appears to be getting harder and harder to have ideas early in life.