  In “Is the class of classes not subordinate to themselves subordinate to itself?” (1914) Leśniewski offers his first published analysis of Russell’s Paradox, claiming that ‘the class of \(A\)s’ refers to the unique mereological sum of \(A\)s, so that since every object is subordinate to itself, no class of objects is not subordinate to itself, and Russell’s Paradox fails to arise. The non-standard term ‘subordinate to’ which he took from Łukasiewicz, is defined by Leśniewski as follows. An object \(P\) is subordinate to a class \(K\) if and only if, for some a, \(K\) is a class of \(a\)s (a mereological sum of \(a\)s, as we shall see), and \(P\) is an \(a\). Let \(P\) be a hemispherical part of a sphere \(Q\). The class of all hemispheres of \(Q\) is, on Leśniewski’s understanding, simply \(Q\) itself, so \(P\) is subordinate to \(Q\). In fact, according to this view, any object is a class, and subordinate to itself. Leśniewski retained this “concrete” understanding of classes throughout his life, claiming that it conformed to Cantor’s own statements. That other set theories gave a different account of things was in Leśniewski’s view their problem, not his.