 From traditional metaphysics Bolzano adopts the doctrine that everything real is either a substance or an adherence (cf. Schnieder 2002). Substances are either themselves simple or composed of simple substances; simple substances (i.e., monads, according to Leibniz) are called ‘atoms’ by Bolzano. The soul is a simple substance. Bolzano attempts to prove that no simple substance can begin or cease to be (in time). This attempt at a proof on Bolzano’s part, however, is deficient, as he himself observed. From this brief sketch it is already evident that Bolzano’s metaphysical views bore a definite stamp from the tradition, especially from Leibniz. In contrast with Leibniz’s doctrine of the “windowlessness” of the monads and of the pre-established harmony that this requires, however, Bolzano assumes an interaction among the finite atoms or monads. (Cf. Bolzano 1827, 48–50, 67, 92 f., 114 f., 2nd edition: 421, 441; Bolzano 1851, reprint 1975: 112 f., 118, E: Russ 2004, 666 f., 670; Příhonský 1857, 7.)