206 THE MECHANISM OF LIFE 



of the radius of the orbit of Neptune — that is, the limit of our 

 solar system — and so it is itself an infinitesimal. But the diameter 

 of the solar system is also an infinitesimal when compared with 

 the distance of the nearest fixed star (about 3| light years, or 

 3-25x6 billions of miles). Now let the reader calculate for him- 

 self this series of magnitudes in terms of the same unit (say a 

 kilometre), and he ought to have little difficulty in seeing that 

 any one, however small or great, may ,have significance with 

 regard to some other one. 



Consider now intervals of time. It is said that an ordinary 

 person can easily realise, or feel, the lapse of duration represented 

 by bV second of astronomical time, and certainly one second may 

 in some circumstances be a rather prolonged period. Now, 

 5V second is about j^ oVo o-niillionth of an ordinary lifetime (that 

 is, it is about 10"-^^ lifetime), and thus, with respect to the lapse 

 of duration which we may call the standard one, 5V second is an 

 infinitesimal of the first order. But in looking at a red light for 

 that length of time we receive some 400 billions of ether vibrations 

 of a certain length — that is to say, 4x10-^'* separate events or 

 things that actually happen. One of these events, therefore, has 

 a duration of 2 X 10 ~ ■'■^ seconds, and this we call an infinitesimal 

 of the second order with respect to the lapse of a lifetime. 



Probably life itself has existed on the earth for 1,000 million 

 years, so that even a very long lifetime is only about i^j-millionth 

 of the whole life-period of the globe. But the latter (10'^ years) 

 must itself be only an infinitesimal fraction of the period of time 

 during which our solar system has been in existence. 



The Meaning of Duration. — For men and women this period 

 of 5V second of astronomical time is to be regarded as an unitary 

 lapse of duration: it is the smallest period for which one may 

 exist as a conscious, sentient being. While it passes, a star 

 moves through an arc of about 1-5 seconds — that, is, a shift in 

 the sky which can easily be measured by refined astronomical 

 methods. In looking at red light for the same period one 

 gathers up into perception some 400 billions of ether vibrations, 

 each of which has a wave-length of 8x10"^ cm. In listening 

 to the note on the piano which is three octaves above the middle 

 C one combines together about forty-one separate vibrations of 

 the atmosphere to make a sound of a certain quality. Our 

 rhythm of duration (in Bergson's phrase) is therefore such that 

 we synthesise these motions, or changes, to make unitary. 



