Abstract
This essay explains the meaning of knowledge and perception as well as different kinds and levels of them, moreover, illuminates sense perception from Avicenna, Surawardi and Mulla sadra’s point of view. Avicenna and Surawardi define knowledge and perception differently. But Mulla sadra criticized their explanations innovating in the definition of knowledge and perception. He believed the origin of knowledge and perception is Existence but not Essence. In Avicenna’s eye, knowledge and perception are divided into four main categories: 1: Sensory, 2: Imaginary, 3: Illusory, 4: Intellectual although Mulla sadra and Surawardi divided them into three categories. Having a closer look, surawardi inserted illusory knowledge in imaginary one, but Mulla sadra inserted it in intellectual knowledge. Avicenna regards sense knowledge as material one while it is regarded as abstract knowledge in Mulla sadra’s eye. In fact, Mulla Sadra regards the created form by soul similar to the form of appearance as sense knowledge.