Parallels and affinities between Spinoza’s philosophy and the philosophy of Platonism include central characteristics of Spinoza’s metaphysics and theory of knowledge, as well as decisive aspects of the geometric method. Spinoza’s treatment of the highest principle and source of being and knowledge, the substantia infinita, his arguments for its singularity, existence, infinity, eternity, causality, transcendence and immanence, its relationship to the attributes and finite modes, in particular to human beings, echo essential features of the treatment of the same problems in Platonic and Platonist philosophy. His understanding of the paradoxical unity of freedom and necessity in the highest principle, and the aim of their reconciliation in the finite intellect by means of the ascent of cognition, culminating in scientia intuitiva and the intellectual love of God, are clearly prefigured in Plotinus, Proclus and their model Plato, as well as in Renaissance Platonists like Marsilio Ficino, Leone Ebreo (Judah Abrabanel or Abravanel, ca. 1460 – 1523), and Abraham Cohen Herrera (c. 1570-c. 1635). In this paper, I argue for a Platonist interpretation of Spinoza, which enables a better understanding of central problems in Spinoza's philosophy, in particular Spinoza's understanding of the paradoxical unity of transcendence and immanence of the substantia infinita, which led to accusations of Spinoza's pantheism and atheism ; and the paradoxical unity of freedom and necessity, which led him to be viewed as a determinist and fatalist. As a case in point, I trace the roots of the geometric method to Proclus' Commentary on the First Book of Euclid's Elements as mediated through Abraham Cohen Herrera's Neoplatonic interpretation of the kabbalah and of dialectic as a method mirroring the procession from, conversion and return of reality to its infinite source.