The old have moreover a tendency to pity, but not on the same principle with the young; for the latter are thus disposed from their love of human nature; the former from their imbecility. Whence they are querulous, and neither facetious nor fond of mirth; for querulousness is the very reverse of fondness for mirth. Such is the disposition of those in advanced life.”—THEODORE BUCKLEY. The writings of Aristotle exhausted the fields of art and science; 400 treatises, most of which have perished, at one time bore his name. Rhetoric, psychology or mental science, and natural history, owed to him their origin. In his “Organon” was first presented the method of _deduction_,—the process by which the mind reasons down from general propositions to particular cases, by means of the _syllogism_, the _organ_ or instrument of reasoning. Men had thus arrived at conclusions for ages, without any knowledge of Aristotle’s formulæ, just as they had talked correctly though ignorant of analytical grammar. It was reserved for the Stagirite to discover the laws by which they drew conclusions, and thus at once to found and perfect LOGIC. This was the science of _reasoning_, as contrasted with Plato’s _dialectics_ or method of _discussing_. (_See Benn’s “The Greek Philosophers.”_) Nor was Aristotle unacquainted with Induction, the great lever of modern philosophy. This process, which reverses the steps of deduction,[36] and reasons from particular cases up to general laws, was employed in his researches, but was not fully developed till twenty centuries later in the “Novum Organon” of Lord Bacon, opening the way to a new era in scientific investigation. Aristotle willed his writings to his disciple Theophrastus, whom we shall next consider; and for many years they were kept from the world, while numerous imitations and forgeries gained the popular ear through the prestige of Aristotle’s name. It was not till 50 B.C. that a complete edition of the genuine works was published, and then at Rome. Meanwhile the Lyceum had waned; its later heads were men of mediocre ability, and the Peripatetic School was superseded in popular estimation by the Epicurean and the Stoic. =Theophrastus=, of Lesbos (374-287 B.C.), a pupil of Plato and afterward of Aristotle, succeeded the latter, by his appointment, as head of the Lyceum. During his time, he maintained the high reputation of the school, attracting many to it from all parts of Greece by his eloquence. That he might address a still larger audience, he wrote numerous treatises on philosophy and natural history.