Abstract
The question of what a form is and whether it is substance or breadth is one of the basic questions in ancient and Islamic philosophies and the answer to it has been one of the most important and first concerns of philosophers. Among the philosophers, the views of Ibn Sina (following Aristotle) and Suhrawardi are more interesting than those of other philosophers. Ibn Sina has accepted the form and essence of it and its function in the substance and the needlessness of the substance to the accidence and the need for the accidence to the substance and has justified his speech with several supporting arguments. In contrast to Suhrawardi, he challenges and abandons the Aristotelian-Ibn Sinai view and offers a new understanding of the outside world. In this article, these two views have been explained, analyzed and evaluated with an analytical method and with the aim of correctly understanding the reality, and it has been concluded that Suhrawardi's view is more justified and explanatory in comparison with Ibn Sina's view.