In this chapter, I argue that the thesis that conceivability entails metaphysical possibility is analytically true, because the objects of our acts of conceiving are individual essences — the building blocks of possible worlds.¹ I specify two distinct modes of conceivability, refute the most common objections raised against the thesis that conceivability entails metaphysical possibility, and reflect on modal rationalism, rational intuition, and the intelligibility of the infinite realm of possible worlds. I show that my concept of conceivability provides a sound model of rational intuition.