INTRODUCTORY 13 



Of the magnitude of this emancipation, and of the severity of the 

 struggle against deep-rooted authority, one could form a faint idea 

 from experience even in my own youth. Our young minds were so 

 deeply imbued with the involuntary feeling that the ancients were 

 superior to us moderns in each and every respect, that not only the 

 hardly re-attainable plastic art of the Greeks and the immortal songs 

 of Homer, but all the mental products of antiquity seemed to us 

 models which could never be equalled; the tragedies of Sophocles 

 were for us the greatest tragedies that the world had ever seen, the 

 odes of Horace the most Ijeautiful poems of all time ! 



In the domain of natural science the new era began with the 

 overthrow of the Ptolemaic cosmogony, which, for more than a 

 thousand years, had served as a basis for astronomj^. When the 

 German canon, Nicolas Copernicus (born at Thorn. 1473, died 1543), 

 reversed the old theory, and showed that the sun did not revolve 

 round the earth, but the earth round the sun, the ice was broken and 

 the way paved for further progress. Galilei uttered his famous 

 ' e pur si muove,' Kepler established his three laws of the movements 

 of the planets, and Newton, a centur}^ later, interpreted their courses 

 in terms of the law of gravitation. 



But we have not here to do with a history of physics or 

 astronomy, and I only wish to recall these well-known facts, in 

 order that we may see how increased knowledge in this domain was 

 always accompanied by advances in that of biology. 



Here, however, we cannot yet chronicle any such thoroughgoing 

 revolution of general conceptions ; the basis of detailed empirical 

 knowledge was not nearly broad enough for that, and it was in the 

 acquiring of such a foundation that the next three centuries, from 

 the sixteenth to the end of the eighteenth, were eagerly occupied. 



The first step necessary was to collate the items of individual 

 knowledge in regard to the various forms of life, and to bring the 

 whole in unified form into general notice. This need was met for 

 the first time by Conrad Gessner's Thierhuch, a handsome folio 

 volume, printed at Zurich in 1551, and embellished with numerous 

 woodcuts, some of them very good. This was followed, in j 600, by 

 a great work in many volumes, written in Latin, by a professor of 

 Bologna, Aldrovandi. Not native animals alone but foreign ones also 

 were described in these works, for, after the discovery of America 

 and the opening up of communication with the East Indies, many 

 new animal and plant forms came to the knowledge of European 

 nations by way of the sea. Thus Francesco Hernandez (died i6co), 

 physician in ordinary to Philip II, descriljed no fewer than forty new 



