Proper Classes Kees Doets A formula $\Phi(x)$ in the one nonĀ­logical symbol $E$ with one free variable $x$ is Russell if the sentence $\not \exists r \forall x (x E r \iff \Phi(x))$ is logically valid. This note describes a pattern common to the classical examples of Russell formulas, adds a couple of new ones, and constructs many formulas that are nearĀ­Russell.