Have the component parts of the world of nature - the inanimate, plants, animals, and human being - been the same from the beginning of the universe or one is a changed form out of another, i.e. a change from the inanimate into plants, from plants into animals and from animals into human beings? There is a general point of view which can be traced back to the time prior to Socrates, the myths of China and ancient India that the universe, as it is now, was suddenly created with its biodiversity and each of the four parts of nature - the inanimate, plants, animals and human beings - are created and vanished repeatedly. No evolution is seen in their type and essence, and the only changes have been seen is superficial. In this universe, human soul alone has had an opportunity to exist before, or being created at the same time together with the body and when the body attached to it, decays, it always survives by itself (Mulla Sadra 1383Ha). Most of the Moslem philosophers believed the same idea called 'Fixism'. As the history of science has frequently proved, scientists belong to a more immense culture, the ideas of which affect the inquiries they believe important. It also affects the categories with which they interpret or explain their knowledge and the certainties governing their attitud es. So, the interpretation of religious books by theologians is based on theses cultural teachings.Evolution is a new theory upon which the whole world of nature changes so that the whole universe, or some parts of it, is always under constant and increasing change, and in the process of the development, number, variety and complexity of the parts of the world are increasing. Buffon (1707-1788) and Lamarck (1744-1829) in the eighteenth century were the pioneers of evolution theory in biology, but Darwin (1809-1882), in the nineteenth century, by offering various documents made this theory testable. The first theories were simple, obscure and less scientific but, little by little, it became more stable and today, very few people don't believe in the theory of evolution (Encyclopedia of the Islamic World 1383H), and even it is irrationally generalized to other areas (Bowler 2000). Although the theory of evolution, either from philosophy or science point of view, has had a recording ancient Greece and among the Muslims such as Ikhwan al-Safa (Ikhwan al-Safa 1995) and the philosophers like Ibn Miskawayh (1338H; 1365H), its discussions have become controversial, in the new era, and as a scientific theory, from the beginning of its proposal, have encountered agreement and opposition especially by some religious people (Bowler 2000). Unfortunately, the theory of evolution has not been discussed seriously from Islamic philosophy point of view. The ancient philosophies such as Platonism, Aristotelianism, peripateticism and the school of illumination cannot answer the questions regarding the relation between natural creatures and the theory of evolution, but this theory not only can be in the same category with Mulla Sadra's geometry knowledge but they are congruous and one who believes in Mulla Sadra's geometry knowledge cannot oppose the evolution of creatures, including human being. This article is going to prove that Mulla Sadra's philosophical thought not only is in agreement with the theory of biological evolution but it is its requirement. Mulla Sadra (1572/ 1640), in the seventeenth century, had stated some aspects of this theory prior to the biologists like Bowfin, Lamarck and Darwin. After offering a brief sketch of biological theory of evolution, this article is trying to investigate the congruency of Mulla Sadra's thoughts with it and will explain his philosophy in defining the evolution of the species.Theory of Evolution, a SketchMany ancient philosophers believed that God created the universe at once, and in the same way as present time, and all species have always been the same. The theory of the evolution of the natural creatures, of course, was discussed as a theory, more or less, among the Roman, Greek and Muslim philosophers. …