Classical Greek philosophy in its struggle to grasp the material world from its very beginning has been marked by the – sometimes undercurrent, some others overt and even intense, but never idle – juxtaposition between the mind and the senses, logos and perception or, if the anachronism is allowed, between realism and idealism. Parmenides is reportedly the first philosopher to insistently assert that thought and being are the same by his famous aphorism τὸ γὰρ αὐτὸ νοεῖν ἐστί τε καὶ εἶναι, (...) and that the “way of truth”, as opposed to the “way of opinion”, only runs through the intellect, since the truth is unattainable by the illusory senses. Thus, true may be only what our intellect can firmly grasp, and – by an easy, though not equally sound step – vice versa: that which our intellect can firmly grasp is necessarily true. In this paper I intend to set off Parmenides’ apparent influence on Anselm with regard to the latter’s celebrated ontological argument concerning the existence of God, and the influence of both on Spinoza’s Ethica, which is founded on the key tenet that not only does God necessarily exist – since God is intellectually conceivable –, but that God also by necessity is an utterly good one. (shrink)