Shaikh S̱ẖahābal Dīn Suhrawardī, known as S̱ẖaiḵẖal Is̱ẖrāq Maqtūl was born about the middle of the 12{th} century. He studied philosophy with Majd Jīlī--the teacher of the commentator Al-Rāzī--and, while still a youth, stood unrivalled as a thinker in the whole Islamic world. His great admirer Al-Malik-al-Zāhir--the son of Sultan Ṣalāḥ-al Dīn--invited him to Aleppo, where the youthful philosopher expounded his independent opinions in a way that aroused the bitter jealousy of contemporary theologians. These hired slaves of bloodthirsty Dogmatism which, conscious of its inherent weakness, has always managed to keep brute force behind its back, wrote to Sultan Ṣalāḥ-al Dīn, that the S̱ẖaiḵẖ's teaching was a danger to Islam, and that it was necessary, in the interest of the Faith, to nip the evil in the bud. The Sultan consented; and there, at the early age of 36, the young Persian thinker calmly met the blow which made him a martyr of truth, and immortalised his name for ever. Murderers have passed away, but the philosophy, the price of which was paid in blood, still lives, and attracts many an earnest seeker after truth. The principal features of the founder of the Is̱ẖrāqī Philosophy are his intellectual independence, the skill with which he weaves his materials into a systematic whole, and above all his faithfulness to the philosophic traditions of his country. In many fundamental points he differs from Plato, and freely criticises Aristotle whose philosophy he looks upon as a mere preparation for his own system of thought. Nothing escapes his criticism. Even the logic of Aristotle, he subjects to a searching examination, and shows the hollowness of some of its doctrines. Definition, for instance, is genus plus differentia, according to Aristotle. But Al-Is̱ẖrāqī holds that the distinctive attribute of the thing defined, which cannot be predicated of any other thing, will bring us no knowledge of the thing. We define "horse" as a neighing animal. Now we understand animality, because we know many animals in which this attribute exists; but it is impossible to understand the attribute "neighing", since it is found nowhere except in the thing defined. The ordinary definition of horse, therefore, would be meaningless to a man who has never seen a horse. Aristotelian definition, as a scientific principle is quite useless. This criticism leads the S̱ẖaiḵẖ, to a standpoint very similar to that of Bosanquet who defines definition, as "Summation of qualities". The S̱ẖaiḵẖ holds that a true definition would enumerate all the essential attributes which, taken collectively, exist nowhere except the thing defined, though they may individually exist in other things.