Was Aristotle an Essentialist?

To speak of the essence of an object is to speak of those intrinsic features that make the object what it is. This view is rooted in Aristotle's philosophy. His metaphysics (the science of being) is built upon the idea that the principle of every real entity (e.g. human being, horse, plant, house) is its essence. In my talk I will challenge this conception of essentialist metaphysics. In the first part, I will give an overview of Aristotle's metaphysical project and I will focus on the enquiry into sensible objects in book Z. In the second part, I will show that his essentialism is exposed to some philosophical difficulties, which lead Aristotle to dismiss it.