Western philosophy has for centuries been mostly devoid of a true metaphysics, but this was not always the case. To refer back to Aristotle and his Scholastic successors, most notably St. Thomas Aquinas, we can gain a clearer understanding of the difference between the reason and the intellect.
Scientific knowledge, for Aristotle, is gained by means of the rational faculty, through discursive reasoning, on the basis of sense data, which provides the raw material of this faculty. Science consists of general conclusions based on this ‘reasoning.’ That is why Aristotle said that ‘there is no science but that of the general.’ Keeping in mind what we said earlier about the difference between the general, which is of the individual order, and the universal, which is beyond that order, Aristotle and Aquinas were essentially acknowledging the limitations of the rational faculty. Over and above this faculty, however, they spoke of the ‘pure intellect,’ which alone had ‘direct’ knowledge of the universal.
This is why Aristotle could say that ‘the intellect is truer than science’, which is to say that the intellect is truer than the faculty on which scientific knowledge is based. He also states that ‘nothing is more true than the intellect’, which is accurate because ‘direct knowledge’ of the universal amounts to an identification with it, for within that order the knower and the known are not distinct. It is also due to the fact of the immediate operation of the pure intellect that the truths apprehended are not subject to doubt, although it is possible that they can, once translated into rational knowledge, could be distorted or only partially retained in the enunciation.
This last observation explains the hesitancy of contemplatives when it comes to sharing their knowledge with others. It is obvious to the possessor of such an experience that they cannot actually convey it without first degrading it, and so the project of translating what they have seen into rational concepts for the sake of verbal communication is a terrifying prospect, lest they betray the truth that it was their privilege to behold.