MATHEMATICAL CONCEPTS ON INTERVAL: Open interval: (a,b) = a < x < b That means, 'x' is neither equal to 'a' and nor equal to 'b'. It lies between a & b. Similarly, "Money" is neither "Valueless" nor "Everything". It lies between"Valueless & Everything". We can say that, Valueless < MONEY < Everything | Quote by Hiten Biswal