---
title: "Physics (Aristotle)"
chunk: 1/4
source: "https://en.wikipedia.org/wiki/Physics_(Aristotle)"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:40:04.675125+00:00"
instance: "kb-cron"
---

The Physics (Ancient Greek: Φυσικής ἀκρόασις, romanized: Physikḗs akróasis, or: Φυσικής ακροάσεως, Physikḗs akroáseōs; Latin: Physica or Naturales Auscultationes, possibly meaning "Lectures on nature") is a named text, written in ancient Greek, collated from a collection of surviving manuscripts known as the Corpus Aristotelicum, attributed to the 4th-century BC philosopher Aristotle.

== The meaning of physics in Aristotle ==
It is a collection of treatises or lessons that deals with the most general (philosophical) principles of natural or moving things, both living and non-living, rather than physical theories (in the modern sense) or investigations of the particular contents of the universe. The chief purpose of the work is to discover the principles and causes of (and not merely to describe) change, or movement, or motion (κίνησις kinesis), especially that of natural wholes (mostly living things, but also inanimate wholes like the cosmos). In the conventional Andronicean ordering of Aristotle's works, it stands at the head of, as well as being foundational to, the long series of physical, cosmological and biological treatises, whose ancient Greek title, τὰ φυσικά, means "the [writings] on nature" or "natural philosophy".

== Description of the content ==
The Physics is composed of eight books, which are further divided into chapters. This system is of ancient origin, now obscure. In modern languages, books are referenced with Roman numerals, standing for ancient Greek capital letters (the Greeks represented numbers with letters, e.g. A for 1). Chapters are identified by Arabic numerals, but the use of the English word "chapter" is strictly conventional. Ancient "chapters" (capita) are generally very short, often less than a page. Additionally, the Bekker numbers give the page and column (a or b) used in the Prussian Academy of Sciences' edition of Aristotle's works, instigated and managed by Bekker himself. These are evident in the 1831 2-volume edition. Bekker's line numbers may be given. These are often given, but unless the edition is the Academy's, they do match any line counts.

=== Book I (Α; 184a–192b) ===
Book I introduces Aristotle's approach to nature, which is to be based on principles, causes, and elements. Before offering his particular views, he engages previous theories, such as those offered by Melissus and Parmenides.  Aristotle's own view comes out in Ch. 7 where he identifies three principles: substances, opposites, and privation.
Chapters 3 and 4 are among the most difficult in all of Aristotle's works and involve subtle refutations of the thought of Parmenides, Melissus and Anaxagoras.
In chapter 5, he continues his review of his predecessors, particularly how many first principles there are. Chapter 6 narrows down the number of principles to two or three.  He presents his own account of the subject in chapter 7, where he first introduces the word matter (Greek: hyle) to designate fundamental essence (ousia). He defines matter in chapter 9: "For my definition of matter is just this—the primary substratum of each thing, from which it comes to be without qualification, and which persists in the result."
Matter in Aristotle's thought is, however, defined in terms of sensible reality; for example, a horse eats grass: the horse changes the grass into itself; the grass as such does not persist in the horse, but some aspect of it – its matter – does. Matter is not specifically described, but consists of whatever is apart from quality or quantity and that of which something may be predicated. Matter in this understanding does not exist independently (i.e. as a substance), but exists interdependently (i.e. as a "principle") with form and only insofar as it underlies change. Matter and form are analogical terms.

=== Book II (Β; 192b–200b) ===
Book II identifies "nature" (physis) as "a source or cause of being moved and of being at rest in that to which it belongs primarily" (1.192b21). Thus, those entities are natural which are capable of starting to move, e.g. growing, acquiring qualities, displacing themselves, and finally being born and dying. Aristotle contrasts natural things with the artificial: artificial things can move also, but they move according to what they are made of, not according to what they are. For example, if a wooden bed were buried and somehow sprouted as a tree, it would be according to what it is made of, not what it is. Aristotle contrasts two senses of nature: nature as matter and nature as form or definition.
By "nature", Aristotle means the natures of particular things and would perhaps be better translated "a nature." In Book II, however, his appeal to "nature" as a source of activities is more typically to the genera of natural kinds (the secondary substance). But, contra Plato, Aristotle attempts to resolve a philosophical quandary that was well understood in the fourth century. The Eudoxian planetary model sufficed for the wandering stars, but no deduction of terrestrial substance would be forthcoming based solely on the mechanical principles of necessity, (ascribed by Aristotle to material causation in chapter 9). In the Enlightenment, centuries before modern science made good on atomist intuitions, a nominal allegiance to mechanistic materialism gained popularity despite harboring Newton's action at distance, and comprising the native habitat of teleological arguments: Machines or artifacts composed of parts lacking any intrinsic relationship to each other with their order imposed from without. Thus, the source of an apparent thing's activities is not the whole itself, but its parts. While Aristotle asserts that the matter (and parts) are a necessary cause of things – the material cause – he says that nature is primarily the essence or formal cause (1.193b6), that is, the information, the whole species itself.