Natural causes.

Aristotle, great Greek philosopher, researcher, reasoner, and writer, born at Stagirus in 384 BC, was the son of a physician. He studied under Plato at Athens and taught there (367–347); subsequently he spent three years at the court of a former pupil in Asia Minor. After some time at Mitylene, in 343–342 he was appointed by King Philip of Macedon to be tutor of his teen-aged son Alexander. After Philip’s death in 336, Aristotle became head of his own school (of “Peripatetics”), the Lyceum at Athens. Because of anti-Macedonian feeling there after Alexander’s death in 323, he withdrew to Chalcis in Euboea, where he died in 322.

Nearly all the works Aristotle prepared for publication are lost; the priceless ones extant are lecture-materials, notes, and memoranda (some are spurious). They can be categorized as follows:

I Practical: Nicomachean Ethics; Great Ethics (Magna Moralia); Eudemian Ethics; Politics; Economics (on the good of the family); On Virtues and Vices.
II Logical: Categories; Analytics (Prior and Posterior); Interpretation; Refutations used by Sophists; Topica.
III Physical: Twenty-six works (some suspect) including astronomy, generation and destruction, the senses, memory, sleep, dreams, life, facts about animals, etc.
IV Metaphysics: on being as being.
V Art: Rhetoric and Poetics.
VI Other works including the Constitution of Athens; more works also of doubtful authorship.
VII Fragments of various works such as dialogues on philosophy and literature; and of treatises on rhetoric, politics, and metaphysics.

The Loeb Classical Library® edition of Aristotle is in twenty-three volumes.