But let us turn to his system of metaphysics, and estimate the worth of his contribution to the thought of his country. In order fully to comprehend the purely intellectual side of Transcendental philosophy, the student, says the S̱ẖaiḵẖ, must be thoroughly acquainted with Aristotelian philosophy, Logic, Mathematics, and Ṣūfīism. His mind should be completely free from the taint of prejudice and sin, so that he may gradually develop that inner sense, which verifies and corrects what intellect understands only as theory. Unaided reason is untrustworthy; it must always be supplemented by "Ḏẖauq"--the mysterious perception of the essence of things--which brings knowledge and peace to the restless soul, and disarms Scepticism for ever. We are, however, concerned with the purely speculative side of this spiritual experience--the results of the inner perception as formulated and systematised by discursive thought. Let us, therefore, examine the various aspects of the Is̱ẖrāqī Philosophy--Ontology, Cosmology, and Psychology. Ontology. The ultimate principle of all existence is "Nūr-i-Qāhir"--the Primal Absolute Light whose essential nature consists in perpetual illumination. "Nothing is more visible than light, and visibility does not stand in need of any definition."[127:1] The essence of Light, therefore, is manifestation. For if manifestation is an attribute superadded to light, it would follow that in itself light possesses no visibility, and becomes visible only through something else visible in itself; and from this again follows the absurd consequence, that something other than light is more visible than light. The Primal Light, therefore, has no reason of its existence beyond itself. All that is other than this original principle is dependent, contingent, possible. The "not-light" (darkness) is not something distinct proceeding from an independent source. It is an error of the representatives of the Magian religion to suppose that Light and Darkness are two distinct realities created by two distinct creative agencies. The ancient Philosophers of Persia were not dualists like the Zoroastrian priests who, on the ground of the principle that the one cannot cause to emanate from itself more than one, assigned two independent sources to Light and Darkness. The relation between them is not that of contrariety, but of existence and non-existence. The affirmation of Light necessarily posits its own negation--Darkness which it must illuminate in order to be itself. This Primordial Light is the source of all motion. But its motion is not change of place; it is due to the _love_ of illumination which constitutes its very essence, and stirs it up, as it were, to quicken all things into life, by pouring out its own rays into their being. The number of illuminations which proceed from it is infinite. Illuminations of intenser brightness become, in their turn, the sources of other illuminations; and the scale of brightness gradually descends to