The faculty called `Intuition' or Buddhi, being utterly and totally transcendent of what we call mind, sometimes also spoken of as the TRUE REASON ... is what can grasp, and instantly comprehend by DIRECT UNION with [so to speak] the essence of the chair, crystal, etc.
It was of such a SPIRITUAL-DIVINE Faculty, and no less, present in latent form within every human being, which The Christ spoke of when He uttered the phrase: "There is a PEACE, which passeth Understanding." And that Peace, for the record, is what obtains the moment one enters Nirvana, or experiences the Atmic faculty of Consciousness [and Being]. Such experience comes for brief moments in what is called Satori, or Samadhi, yet only fully applies at Mukti, Moksha, Liberation, Enlightenment, or what Christians speak of as Salvation.
True Nirvanic attainment only occurs at the long end of our evolution, whereas hundreds upon thousands of individuals have had momentary or longer experiences of it ... and typically, if you have, you KNOW it. Again, such KNOWLEDGE, being certain, removes all shadow of a doubt - at least regarding that particular experience. True removal of Doubt is itself a stage marking some considerable advancement upon the spiritual Path, whose entrance is sometimes marked by the `2nd Birth' or Born-again experience, the birth of the Christ in the human heart.
Science will be able - soon enough - to verify what I have said in these few paragraphs, yet from a more secular viewpoint. This changes nothing, yet will be more palatable for certain types of people ... and rightly so. I just comment from my own experience and with terminology which I have learned and become accustomed to.
Namaskar