The works on Natural Science comprise the Physics in eight books, treating of the general principles and relations of nature; four books On the Hearens, and two on Beginning and Per ishing. The last treatise is important for a knowledge of Aristotelian philosophy. The Me teorology discusses the phenomena of the heav ens. Natural History is handled in ten books; it are associated the following treatises: Parts of .lnimals in four hooks, Ocncration in five, and Mode of Progression in one. To these must be added certain works of doubtful authen ticity: On Plants in two books, a retranslation from the Latin and probably the work of Nico Jails of Damascus, who composed, under Augus tus, a compendium of Aristotle's philosophy; On the Cosmos, certainly belonging to the Roman period; On the Motion of Animals, On Breath ing, On Colors of Plants and Animals, all later than Aristotle. The treatise on Physiog nomy, which was composed certainly as late as Hadrian's time, is based apparently on two lost works named in the ancient catalogues of the Aristotelian writings. The Problems, discussions chiefly of physical questions, is also drawn in part from the philosopher's work. The Mechan ics, Mirabiles Auscultationes, and some other minor monographs falling within the same field are certainly spurious.
According to Aristotle's own view, psychology was inseparably connected with natural science. Under this head we possess his work On the Soul in three books, and a large number of smaller treatises which are known as the Parva Naturalia.
Next must be named the works on Ethics and Politics, which Aristotle regarded as parts of the same subject. Under the former division there are extant three works: The Nieomachean Ethics in ten hooks, which takes its name from the philosopher's son, Nicomachus, to whom the work is dedicated and by whom it probably was edited. This is Aristotle's work. The Eudemean Ethics in seven books was prepared by Aristotle's pupil Eudemus on the basis of his master's lec tures and the Nieoniachean Ethics, with which it coincides in parts. The Magna Mornlia in two books is a late workof the Peripatetic SchooLand nothing more than an abstract of the other works. An essay On Virtues and Vices is also spurious. The Politics in eight books is closely connected with the Ethics. The work is incomplete but mas terly, discussing the elements and aims of the State, the forms of government, and the ideal State. The loss of the Constitutions, which treat ed of 158 States, is greatly to be regretted; but fortunately the greater part of the Constitution of Athens, which belonged to the larger work, has been recovered in recent years from four papy rus rolls of the First Century A.D., first published by Kenyon in 1891. This document is one of the most valuable for the history of Athens, and has at many points corrected and enlarged our previous knowledge. The Economics in three books is the work of the later School.
In the field of Rhetoric and Poetics, Aristotle also made contributions of the highest value and permanence. Ills Rhetoric in three books treats of the relations of rhetoric to dialectic, the na ture of the proof the orator may employ, the use of examples, and language and style. In this work also appear beginnings of formal gram mar and its technical terms. The Rhetoric ad dressed to Alexander, which is catalogued with Aristotle's works, was written by Anaximenes. Of the Poetics, only the first book on tragedy and epic poetry is preserved, but this is of inestima ble value for its analyses of the various kinds of poetry and its full treatment of tragedy.
From this enumeration of the most important extant writings of Aristotle, the universality of his studies is evident; and in every field enu merated his influence has been enormous. By him Logic, Grammar, Rhetoric, Literary Criti cism, Polities, Psychology, Ethics, Natural His tory, Physiology,were raised to independent disci plines; he was the first to attempt a history of Philosophy and Government. This many-sided
literary activity was the natural result of his method of working, proceeding from the individ ual to the general ; and this method, which col lects facts. compares, sifts, and groups them cording to their relations, and thus obtains sys tematic knowledge of the subject in hand, has heen most fruitful in the history of investigation of every sort, especially in the Nineteenth Cen tury.
Aristotle's service lies in his analysis and clear distinction of ideas and in his studies in par ticular fields, rather than in the full develop ment of a philosophy. Vet here he made impor tant advances that have been influential down to the present clay. According to him, Being has four universal elements: Matter, form or es sence, the efficient cause, and the final cause. These principles enter into the constitution of everything. Matter is mere potentiality, which through the supervention of Form becomes the Actual. By Form, Aristotle wished to replace the Platonic idea, which, lie pointed out, cammt ex ist apart from the individual. Every change from potentiality to actuality is accomplished by an efficient cause which is working toward an end, the Final Cause. In the field of Ethics this final cause is man's sum fn um banum, happiness, which is defined to lie the activity of the soul in accordance with virtue, but. under favorable con ditions. The problem of free-will Aristotle met by the statement that man has a potent iality in two opposite directions—for good or evil—whieh can be freely chosen; by consistently choosing one a man forms the habit of virtue or vice, and thus becomes either virtuous or vicious, as his choice determines. Virtue itself lies between the extremes of self-indulgence and asceticism.
The influence of Aristotle on human thought has continued unbroken to the present day. In the early centuries of our era his writings stimu lated scientific inquiry; during the Middle Ages Latin translations from the Arabic versions guid ed the philosophy of the Western Church, al though the real nature of Aristotelianism was • little understood. Arabian philosophy in the West during the Eleventh and Twelfth centuries was a combination of Aristotelianism with cer tain Neo-Platonic elements. With the revival of learning the original of Aristotle's works became gradually known, and from them were drawn the means to combat the errors of scholasticism.
Learned comment on Aristotle began with the First Century B.C., and during antiquity and the early medheval period the amount of comment grew to be enormous. The standard edition of the works is still that by Bekker (5 vols., 1831-40). Volumes I. and II. contain the Greek text; III., the Latin translations; IV., seholia, edited by Brandis; V., the fragments, edited by Rose, and Bonitz's index. A new and complete edition of the ancient commentaries is being pub lished by the Prussian Academy. Twenty-five volumes have already appeared. Of editions of single works, the following are valuable: Tren delenhurg's Psychology (1877) ; Schwegler-Bo nitz's Metaphysics (1848) ; Ramsauer's Yiuonaaclxean Ethics ( 1878 ) ; Susemihl's Politics (1879) ; Spengel's Rhetoric (1867) ; Vahlen's Poetics (1884). Useful English.works of general import are Grote's Aristotle (1872) ; Grant's Ethics of Aristotle (London and Edinburgh, 1877) ; Bywater. Ethics (1890) ; Jowett, Politics ( 1885 ) ; Newman, Politics ( 1887 ) ; Wallace, Psychology (1884). General bibliography by Schwab, Bibliographic rriristote (Paris, 1896). For influence of Aristotle upon Arabic philoso phy, see ARABIC LANGUAGE; AVERROES.