390 THE WOKLD OF LIFE 



as it is in order to supply us, when the proper time came, with * 

 the means of exploring and studying the inner mechanism 

 of the world in which we live — of enabling us to appreciate 

 its overwhelming complexity, and thus to form a more ade- 

 quate conception of its author, and of its ultimate cause and 

 purpose. 



I have already shown that the postulate of a past eternal 

 existence is no explanation, and leads to insuperable difficulties. 

 A beginning in time for all finite things is thus demonstrable ^ 

 but a beginning implies an antecedent cause, and it is impos- 

 sible to conceive of that cause as other than an all-pervading 

 mind. 



The Mystery of Carbon: the Basis of Organised Matter and 



of Life 



It is universally admitted that carbon is the one element 

 which is essential to all terrestrial life. It will be interesting, 

 therefore, to give a brief statement of what is known about 

 this very important substance. Although it is so familiar to 

 us in its solid form as charcoal, or in a more mineralised form 

 as black-lead or graphite, it is doubtful whether it exists un- 

 combined on the earth except as a product of vegetation. 

 Though graphite (plumbago) is found in some of the earliest 

 rocks, yet it is believed that some forms of vegetation existed 

 much earlier. Graphite has also occurred (rarely) in mete- 

 orites, but I am informed by my friend. Professor Meldola, 

 that it cannot be decided whether this is derived from carbon- 

 dioxide gas or from gaseous carbon. Sir William Huggins 

 was also doubtful as to the state in Avhich it exists in the sun 

 and comets, w^hether as carbon-vapour or a hydrocarbon. But 

 the most interesting point for us is that it exists as a constitu- 

 ent of our atmosphere, of which carbon-dioxide fonns about 

 ^■g^ooth part, equal to about yoVo't^^ ^2iYi by weight of solid 

 carbon ; and it is from this that the whole of the vegetable 

 kingdom is built up. The leaves of plants contain a green 

 substance named chlorophyll, which by the aid of sunlight can 



