128 FKAGMENTS OF SCIENCE. 



welcomes every gleam, and seeks to augment his light 

 by indirect incidences. He studies the methods of 

 nature in the ages and the worlds within his reach, in 

 order to shape the course of speculation in antecedent 

 ages and worlds. And though the certainty possessed 

 by experimental enquiry is here shut out, we are not 

 left entirely without guidance. From the examination 

 of the solar system, Kant and Laplace came to the con- 

 clusion that its various bodies once formed parts of the 

 same undislocated mass; that matter in a nebulous 

 form preceded matter in its present form; that as the 

 ages rolled away, heat was wasted, condensation fol- 

 lowed, planets were detached; and that finally the chief 

 portion of the hot cloud reached, by self-compression, 

 the magnitude and density of our sun. The earth 

 itself offers evidence of a fiery origin; and in our day the 

 hypothesis of Kant and Laplace receives the independ- 

 ent countenance of spectrum analysis, which proves the 

 same substances to be common to the earth and sun. 



Accepting some such view of the construction of 

 our system as probable, a desire immediately arises to 

 connect the present life of our planet with the past. 

 We wish to know something of our remotest ancestry, 

 On its first detachment from the central mass, life, as 

 we understand it, could not have been present on the 

 earth. How, then, did it come there? The thing to 

 be encouraged here is a reverent freedom a freedom 

 preceded by the hard discipline which checks licentious- 

 ness in speculation while the thing to be repressed, 

 both in science and out of it, is dogmatism. And here 

 I am in the hands of the meeting willing to end, but 

 ready to go on. I have no right to intrude upon you, 

 unasked, the unformed notions which are floating like 

 clouds, or gathering to more solid consistency, in the 

 modern speculative scientific mind. But if you wish 



