As the moon cannot give its light unless it is illuminated by the sun, so likewise reason, in order of reality which is its own rightful domain cannot function validly except under the guidance of principles which enlighten and direct it, and which it receives from the higher intellect.
Excerpt: Fundamental Symbols: The Universal Language of Sacred Science, Rene Guenon, Quinta Essentia, 1995, p.291-2
What is true for the sun and the moon is true for the heart and the brain or better, for the faculties to which these two organs correspond and which they symbolise, that is, the intuitive intelligence and the rational or discursive intelligence…Reason, in fact, which is only a mediate knowing faculty, is the strictly human mode of intelligence; intellectual intuition can be called supra-human, as iti s a direct participation in universal intelligence which, residing in the heart, that is, at the being’s very centre where lies his point of contact with the Divine, penetrates this being from within and illuminates him with its radiation.
Light is the most common symbol of knowledge; thus solar light naturally represents direct knowledge, that is, intuitive knowledge which is that of the pure intellect, whereas lunar light represents reflective knowledge, that is, discursive knowledge which is that of the rational faculty. As the moon cannot give its light unless it is illuminated by the sun, so likewise reason, in order of reality which is its own rightful domain cannot function validly except under the guidance of principles which enlighten and direct it, and which it receives from the higher intellect.
On this point there is a misunderstanding which it is important to dispel: modern philosophers are strangely mistaken in speaking as they do of ‘rational principles’ as if these principles belonged rightfully to reason…This is an example of the rationalist error, and one can understand thereby the essential difference which exists between rationalism and true intellectuality. It only needs a moment’s reflection to understand that a principle in the true sense of the word, by the very fact that it cannot be drawn or deduced from something else, can only be grasped immediately, thus intuitively, and could not be the object of a discursive knowledge such as that which characterises reason…Intuitive knowledge because it is immediate is necessarily infallible in itself; on the contrary error can always be introduced into any knowledge that is indirect or mediate such as rational knowledge and one can thereby see how wrong Descartes was in seeking infallibility to reason. This is what Aristotle expresses in these terms: ‘Among the properties of intelligence, in virtue of which we attain to truth, there are some which are always true, and others that can lead into error. The latter case is that of reasoning; but the intellect is always in conformity with truth, and nothing is truer than the intellect…”
This direct perception of truth, this intellectual and supra-rational intuition, the very notion of which modern man seems to have lost, is true ‘heart knowledge’ to use an expression frequently met with in Oriental doctrines. Moreover, this knowledge is in itself something incommunicable; it is necessary to have realised it…It is on supra-rational knowledge that ‘sacred science’ is essentially based…