HIPPARCHUS OF NICEA 9 



varied, with reference to his previous observations. Pro- 

 gress in this direction came about of necessity, as soon as the 

 possibiUties were exhausted of drawing conclusions from 

 casual and remembered observations of processes taking 

 place by themselves all around us. The essential advance 

 was in the direction of a more consciously and advantageously 

 chosen alteration of the conditions of experiment; a step 

 which proved fertile in results. Progress in this manner of 

 investigation had already commenced in antiquity; it was 

 interrupted, together with all other investigation, for fifteen 

 hundred years, to be again taken up more particularly by 

 Galileo - but even in his case not suddenly, but only step 

 by step - and again developed further. The assertion that 

 the investigation of nature in the form of experimental 

 science did not exist before our era, is contradicted by the 

 example of Hipparchus alone, who may be regarded as the 

 actual founder of astronomy based upon comprehensive 

 observation and the collection of experimental data. 



LEONARDO DA VINCI 



1452-1519 



Leonardo was the first great man of the new epoch. He 

 was born in Vinci near Empoli, not far from Florence, and 

 there received his early training as a painter and musician. 

 In the latter capacity he was received at the court of Milan, 

 where he painted his famous 'Last Supper.' He was no less 

 active as an artist, and as adviser during the construction of 

 the fortifications and canals. He also appears to have founded 

 an academy for art and science in Milan, of which he him- 

 self formed the centre. War put an end to all this splendid 

 development after nineteen years. Leonardo then returned 

 to Florence. He later sought once again a field for his 



