The Ṣafavid twelver shiʿi polymath by the name of Mulla Muḥsin-Muḥammad (1007/15991090/1679), nicknamed al-Fayḍ al-Kāshānī, was known as an exegete, a traditionist, a theologian, a philosopher and a mystic. This article will argue that al-Kāshānī’s epistemological framework in ʿAyn al-yaqīn (Certainty Itself), written in 1627, is founded upon the simultaneous distinction and integration of three epistemological paradigms: 1. demonstrative reason, 2. mystical unveiling and 3. divine revelation. Al-Kāshānī’s epistemological position is particularly intriguing because the three epistemic resources are true on two levels. First, each is true in itself despite its relationship with the other two epistemic resources. Second, the interaction of all three are deemed to yield higher harmonies of epistemic verity. Hence, the distinction between the spheres of 1. demonstrative reason, 2. mystical unveiling and 3. divine revelation does not entail their lack of correlation from al-Kāshānī’s epistemic stance.