When I first read this book, I found it extremely original: certainly, although I had read serious philosophy before, I had never thought about it: ideas and beliefs are different, but we usually think of some thoughts as ideas, while in fact they are just beliefs. We have ideas, but we are IN beliefs. We create ideas, but we don't create beliefs: we adopt them. Beliefs are the basic intellectual assumptions upon which we build our view of the world. Following our reason, and building upon those beliefs, we develop ideas. For example: I have never been to Australia, but I am certain it exists. That's not an idea; it's a belief. This essays are very useful to understand the different categories of thoughts that our mind bears and produces. The style is clear and straightforward, as usually with Ortega.

The rest of the essays verse about Herbart, a German Romantic philosopher, from whom Ortega analyses his most relevant work, that on psychology and pedagogy, and about psychoanalysis, the perception about other people, sincerity, the dilemma reason/feelings, partisanship as an attitude.