GALILEO GALILEI 25 



the smallest to the greatest, from the atoms to the planets 

 and suns in cosmic space, is only motion of them or their 

 parts, Galileo thereby founded the whole physics of matter. 

 The investigation of cases of equilibrium (statics) in which 

 motion does not occur had no doubt to come first, since it is 

 simpler, and we saw how this had been studied from the 

 earliest times down to Stevin. But the general and most 

 important case is one in which the conditions of equilibrium 

 are not fulfilled, and we have motion taking place. 



All the writings of Galileo show us that before his time 

 no one had been able to recognise in detail the character of 

 even so simple a motion as that of a falling or projected stone, 

 and still less to calculate the course of such motion in ad- 

 vance; it had always remained a dimly realised transition, 

 from one position of equilibrium to another, the expression 

 of an imagined striving of every body to reach its 'natural 

 position' where it belongs. How great is the difference be- 

 tween this stage of knowledge and our present ability to pre- 

 dict all phenomena of motion, as soon as the masses moved 

 and the forces acting are sufficiently known! This forms the 

 whole foundation of present-day mechanics, acoustics, and 

 theory of heat, which together make up the physics of mat- 

 ter. As a later and further part of physics we have the physics 

 of the ether, which goes beyond Galileo; but even the know- 

 ledge that this is the case has only come to us quite recently, 

 so that until a short time ago, Galileo could be regarded as 

 the founder of the whole of physics. His achievements in 

 detail may be gathered from the following account of his 

 experiences; did this refer to several men and not to one 

 alone, they would all be individually among the greatest 

 scientists. 



Galileo came from an old and respected Florentine family. 

 His father appears to have been a merchant, but was also a 

 teacher of music, and known as author of works on music. 

 His son also inherited a love of this art, and even unusual 



