INTRODUCTION. 7 



before his time, and since its destruction by earthquakes and 

 inundations navigation in the Atlantic had been impossible 

 owing to the fine mud and detritus left by the vanished land. 



The work of Aristotle (384-322 B c.) marks the culminating 

 point reached by the Greeks, both in the domain of speculative 

 philosophy and in that of empirical observation. Although 

 the physical and geological researches of the great Stagirite 

 embrace less of original discovery than his researches in 

 zoology and physiology, they group and define more precisely 

 the best results of the Eleatic, Pythagorean, and Atomic 

 philosophers, re-animate them with new thoughts, and fre- 

 quently place them on a true scientific basis. Aristotle departs 

 from the atomic philosophers in assuming that matter is diverse 

 in quality, and that the universe is divided into an earthly and 

 a heavenly half; the imperishable ether belongs to the heavenly 

 half, while the four elements, earth, water, air, and fire, com- 

 pose the earth and the planets. The earth forms, in Aristotle's 

 conception, the stationary centre of the universe round which 

 the planets move to the left ; beyond their orbits is the great 

 ethereal circle of the heavens in which the stars move towards 

 the right. The development of the earth is comparable with 

 that of an organism ; it has periods of growth, maturity, and 

 decay. During recurring periods of rejuvenescence the lower 

 animals take origin in the mud of the earth, and from them 

 develop, by sexual generation, the higher groups of animals. 

 The plants are related to animals, and the different kinds of 

 animals to one another by numerous transitional forms. Aris- 

 totle's works seldom treat special geological questions, and his 

 meteorology, although it discusses earthquakes, the alternation 

 of continent and ocean, the Deucalion flood and inundations 

 of the Nile, does not contribute much that is new. 



Theophrastus of Lesbos (368-284 B.C.), the most famous 

 pupil of Aristotle, devoted himself chiefly to scientific studies. 

 In addition to his valuable botanical treatises, he gave much 

 information about minerals and fossils in a fragmentary treatise 

 " On Stones." A special work on fossils, with which Pliny 

 was apparently acquainted, has since been lost. 



The Encyclopaedists of the Alexandrine school occupied 

 themselves chiefly with astronomy, mathematics, and geo- 

 graphy. Eratosthenes (276-196 B.C.) by his measurement of 

 the degree in Egypt for the first time laid the foundation 

 of a more exact estimate of the size of our planet. He 



