As a teenager and an undergraduate, I sometimes experienced an unusual mental state when studying mathematics. This was a state of great happiness and seemed to arise when I was engaged in deep, deductive thinking – for instance, after spending days or weeks attempting to prove or disprove some mathematical statement. The state only arose when I was doring pure mathematics – ie, the theory of mathematics, not its application. It never lasted long – perhaps an hour, at most – and only happened a few times a year. The state did not always arrive, and I never determined what in particular I did, if anything, to provoke it. It was one of the key reasons that I decided to major in pure math at university. For ease of reference, I will refer to this state as one of deductive bliss.