Like his teacher Plato, Aristotle's philosophy aims at the universal. Aristotle's ontology, however, finds the universal in particular things, which he calls the essence of things, while in Plato's ontology, the universal exists apart from particular things, and is related to them as their prototype or exemplar. For Aristotle, therefore, epistemology is based on the study of particular phenomena and rises to the knowledge of essences, while for Plato epistemology begins with knowledge of universal Forms (or ideas) and descends to knowledge of particular imitations of these. For Aristotle, "form" still refers to the unconditional basis of phenomena but is "instantiated" in a particular substance (see Universals and particulars, below). In a certain sense, Aristotle's method is both inductive and deductive, while Plato's is essentially deductive from a priori principles.[26]
In Aristotle's terminology, "natural philosophy" is a branch of philosophy examining the phenomena of the natural world, and includes fields that would be regarded today as physics, biology and other natural sciences. In modern times, the scope of philosophy has become limited to more generic or abstract inquiries, such as ethics and metaphysics, in which logic plays a major role. Today's philosophy tends to exclude empirical study of the natural world by means of the scientific method. In contrast, Aristotle's philosophical endeavors encompassed virtually all facets of intellectual inquiry.