题目内容：
根据下列材料，翻译划线内容。In his lectures at the Lyceum, a school that remained for centuries one of the great centers of learning in Greece, Aristotle defined the basic concepts and principles of many of the sciences.
61 ) In the first place, Aristotle criticized Plato's theory of Forms by arguing that forms could not exist by themselves but existed only in particular things, which are composed of both form and matter. He understood substances as matter organized by a particular form.
Nature, for Aristotle, is an organic system of things whose forms make it possible to arrange them into classes comprising species and genera. Each species, he believed, has a form, purpose, and mode of development in terms of which it can be defined. 62) The aim of science is to define the essential forms, purposes, and modes of development of all species and to arrange them in their natural order in accordance with their complexities of form. The main levels are the inanimate, the vegetative, the animal, and the rational. 63) The soul is the form of the body, and humans, whose rational soul is a higher form than the souls of other species on earth, are the highest species of perishable things. The heavenly bodies, composed of an imperishable substance, or ether, and moved eternally in perfect circular motion by God, are still higher in the order of nature.
Aristotle's political and ethical philosophy similarly developed out of a critical examination of Plato's principles. 64) The standards of personal and social behavior, according to Aristotle, must be found in the scientific study of the natural tendencies of individuals and societies rather than in abstract realm of pure forms. Less insistent therefore than Plato on a rigorous conformity to absolute principles, Aristotle regarded ethical rules as practical guides to a happy and well-rounded life. His emphasis on happiness, as the active fulfillment of natural capacities, expressed the attitude toward life held by cultivated Greeks of his time. In political theory, Aristotle agreed with Plato that a monarchy ruled by a wise king would be the ideal political structure, but he also recognized that societies differ in their needs and traditions and believed that a limited democracy is usually the best compromise. 65) In his theory of knowledge, Aristotle rejected the Platonic doctrine that knowledge is innate and insisted that it can be acquired only by generalization from experience. He interpreted art as a means of pleasure and intellectual enlightenment rather than an instrument of moral education.
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