Epistemology Mulla Sadra's radical ontology also enabled him to offer original contributions to epistemology, combining aspects of Ibn Sina's theory of knowledge (in which the Active Intellect, while remaining utterly transcendent, actualizes the human mind by instilling it with intellectual forms in accordance with its state of preparation to receive these forms) with the theory of self-knowledge through knowledge by presence developed by al-Suhrawardi. Mulla Sadra's epistemology is based on the identity of the intellect and the intelligible, and on the identity of knowledge and existence. His theory of substantial motion, in which existence is a dynamic process constantly moving towards greater intensity and perfection, had allowed him to explain that new forms, or modes, of existence do not replace prior forms but on the contrary subsume them. Knowledge, being identical with existence, replicates this process, and by acquiring successive intelligible forms - which are in reality modes of being and not essential forms, and are thus successive intensifications of existence - gradually moves the human intellect towards identity with the Active Intellect. The intellect thus becomes identified with the intelligibles which inform it.

Furthermore, for Mulla Sadra actual intelligibles are self-intelligent and self-intellected, since an actual intelligible cannot be deemed to have ceased to be intelligible once it is considered outside its relation to intellect. As the human intellect acquires more intelligibles, it gradually moves upwards in terms of the intensification and perfection of existence, losing its dependence on quiddities, until it becomes one with the Active Intellect and enters the realm of pure existence. Humans can, of course, normally only attain at best a partial identification with the Active Intellect as long as they remain with their physical bodies; only in the case of prophets can there be complete identification, allowing them to have direct access to knowledge for themselves without the need for instruction. Indeed, only very few human minds attain identification with the Active Intellect even after death.

Methodology Even this brief account of Mulla Sadra's main doctrines will have given some idea of the role that is played in his philosophy by the experience of the reality which it describes. Indeed he conceived of hikma (wisdom) as 'coming to know the essence of beings as they really are' or as 'a man's becoming an intellectual world corresponding to the objective world'. Philosophy and mysticism, hikma and Sufism, are for him two aspects of the same thing. To engage in philosophy without experiencing the truth of its content confines the philosopher to a world of essences and concepts, while mystical experience without the intellectual discipline of philosophy can lead only to an ineffable state of ecstasy. When the two go hand in hand, the mystical experience of reality becomes the intellectual content of philosophy. The four journeys, the major sections into which the Asfar is divided, parallel a fourfold division of the Sufi journey. The first, the journey of creation or the creature (khalq) to the Truth (al-haqq), is the most philosophical; here Mulla Sadra lays out the basis of his ontology, and mirrors the stage in the Sufi's path where he seeks to control his lower nafs under the supervision of his shaykh. In the second journey, in the Truth with the Truth, the stage at which the Sufi begins to attract the divine manifestations, Mulla Sadra deals with the simple substances, the intelligences, the souls and their bodies, including therefore his discussion of the natural sciences. In the third journey, from the Truth to creation with the Truth, the Sufi experiences annihilation in the Godhead, and Mulla Sadra deals with theodicy; the fourth stage, the journey with the Truth in creation, where he gives a full and systematic account of the development of the human soul, its origin, becoming and end, is where the Sufi experiences persistence in annihilation, absorbed in the beauty of oneness and the manifestations of multiplicity.

Mulla Sadra had described his blinding spiritual realization of the primacy of existence as a kind of 'conversion'. In the earlier days I used to be a passionate defender of the thesis that the quiddities are the primary constituents of reality and existence is conceptual, until my Lord gave me spiritual guidance and let me see His demonstration. All of a sudden my spiritual eyes were opened and I saw with utmost clarity that the truth was just the contrary of what the philosophers in general had held.... As a result

[I now hold that] the existences (wujudat) are primary realities, while the quiddities are the 'permanent archetypes' (a'yan thabita) that have never smelt the fragrance of existence. (Asfar, vol. 1, introduction)

Therefore it is not surprising that Mulla Sadra is greatly indebted to Ibn al-'Arabi in many aspects of his philosophy. Ibn Sina provides the ground on which his metaphilosophy is constructed and is, as it were, the lens through which he views Peripatetic philosophy. However, his work is also full of citations from the Presocratics (particularly Pythagoras), Plato, Aristotle, the Neoplatonists and the Stoics (taken naturally from Arabic sources), and he also refers to the works of al-Farabi, and Abu'l Hasan al-'Amiri, who had prefigured Mulla Sadra's theory of the unity of intellect and intelligible. This philosophical heritage is then given shape through the illuminationism of al-Suhrawardi, whose universe of static grades of light he transformed into a dynamic unity by substituting the primacy of existence for the latter's primacy of quiddity. It is in this shaping that the influence of Ibn al-'Arabi, whom Mulla Sadra quotes and comments on in hundreds of instances, can be most keenly felt. Not only is that apparent in Mulla Sadra's total dismissal of any role for quiddity in the nature of reality, but in the importance which both he and Ibn al-'Arabi gave to the imaginal world ('alam al-mithal, 'alam al-khayal).

In Ibn Sina's psychology, the imaginal faculty (al-quwwa al-khayaliyya) is the site for the manipulation of images abstracted from material objects and retained in the sensus communis. The imaginal world had first been formally proposed by al-Suhrawardi as an intermediate realm between that of material bodies and that of intellectual entities, which is independent of matter and thus survives the body after death. Ibn al-'Arabi had emphasized the creative aspects of this power to originate by mere volition imaginal forms which are every bit as real as, if not more real than, perceptibles but which subsist in no place. For Mulla Sadra, this world is a level of immaterial existence with which it is possible for the human soul (and indeed certain higher forms of the animal soul) to be in contact, although not all the images formed by the human soul are necessarily veridical and therefore part of the imaginal world. For Mulla Sadra, as also for Ibn al-'Arabi, the imaginal world is the key to understanding the nature of bodily resurrection and the afterlife, which exists as an immaterial world which is nevertheless real (perhaps one might say more real than the physical world), in which the body survives as an imaginal form after death.

Philosophy has always had a tense relationship with theology in Islam, especially with the latter's discourse of faith (iman) and orthodoxy. In consequence, philosophy has often been seen, usually by non-philosophers, as a school with its own doctrines. This is despite the assertions of philosophers themselves that what they were engaged in was a practice without end (for, as Ibn Sina had declared that what is known to humankind is limited and could only possibly be fulfilled when the association of the soul with the body is severed through death), part of the discipline of which consisted in avoiding taqlid, an uncritical adherence to sects (see Islam, concept of philosophy in). It is the notable feature of Mulla Sadra's methodology that he constantly sought to transcend the particularities of any system - Platonic, Aristotelian, Neoplatonic, mystical or theological - by striving to create through his metaphilosophy an instrument with which the soundness of all philosophical arguments might be tested. It is a measure of his success that he has remained to the present day the most influential of the 'modern' philosophers in the Islamic world.