The idea arrived on your walk. It began at your desk.

Wallas draws them from single achievements of thought, traced from beginning to end. Preparation: the problem is investigated “in all directions.” Incubation: you stop thinking about it consciously, by working on something else or by resting. Illumination: the “happy idea” appears, often announced by what Wallas calls Intimation, the sense that a solution is on its way. Verification: the idea is tested and given exact form. In the daily stream of thought, he adds, the four stages “constantly overlap each other,” so the course treats them as a map, not a ritual.

No. Wallas draws on Helmholtz and Poincaré, but also on a preacher preparing a sermon, a civil servant at a difficult problem, an administrator choosing the day’s priority, and “a business man going through his morning’s letters.” The course stays with ordinary scenes: a birthday speech, a vague brief at work, a neighborhood exhibition, a kitchen table with no room for dinner. You do not have to call yourself creative. It is enough to want a thought of your own, not only a borrowed one.

Briefly, in two lessons, and only where it sheds light on Wallas. Benjamin Baird and colleagues (2012) found that people who spent a break on an undemanding task that let their minds wander improved more on unusual-uses problems they had already seen than some comparison groups. A 2009 review by Ut Na Sio and Thomas Ormerod found that the benefits of incubation varied with the task and the conditions. Marily Oppezzo and Daniel Schwartz (2014) found that walking helped people come up with varied, appropriate ideas, though not every kind of task benefited equally. The course presents these as parallels to Wallas’s account, with their limits, and keeps the focus on his book.

29 episodes, about two and a half hours in English: an introduction, 18 lessons of about six minutes each, three readings of Wallas’s own pages, two recaps, four conversations on the questions that may remain, and a short closing. In Ukrainian the course runs about 2 hours 45 minutes. The complete text in English and Ukrainian, the quotes, the introduction and the first three lessons are free in the Audeno app on iPhone. One purchase, 4.99 USD in the US and adjusted by country, opens the whole audio course in English and Ukrainian, and in any language added later. No subscription, and the course can be downloaded for listening offline.

The complete audio course of this book, all 29 episodes, in every language it has now and every language added later. One purchase at the App Store price, $4.99 in the United States, adjusted by country. No subscription.

Yes. Each lesson downloads the first time you play it and then stays on the iPhone; a course you own can be downloaded whole for listening with no connection. The text and quotes are inside the app.