The Physics (Greek: Φυσικὴ ἀκρόασις or phusike akroasis; Latin: Physica, or Physicae Auscultationes, meaning "lectures on nature") of Aristotle is one of the foundational books of Western science and philosophy. As Martin Heidegger once wrote,The Physics is a lecture in which he seeks to determine beings that arise on their own, τὰ φύσει ὄντα, with regard to their being. Aristotelian "physics" is different from what we mean today by this word, not only to the extent that it belongs to antiquity whereas the modern physical sciences belong to modernity, rather above all it is different by virtue of the fact that Aristotle's "physics" is philosophy, whereas modern physics is a positive science that presupposes a philosophy.... This book determines the warp and woof of the whole of Western thinking, even at that place where it, as modern thinking, appears to think at odds with ancient thinking. But opposition is invariably comprised of a decisive, and often even perilous, dependence. Without Aristotle's Physics there would have been no Galileo.
It is a collection of treatises or lessons that deal 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 (kinesis), especially that of natural wholes (mostly living things, but also inanimate wholes like the cosmos). In the conventional Andronichean 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 on nature" or "natural philosophy".