TRACING THE PROGRESS OF SCIENCE. 7 



the first sun-set, or on first hearing his own voice, and 

 you will find it difficult, even if you can reach his 

 probable conceptions, to select adequate language in 

 which to describe them. 



In tracing the progress of science, the difficulty 

 is too often of another kind. We are not so much 

 at a loss, to ascertain what was early known with 

 regard to any department of scientific research, or 

 to describe it to others when ascertained, as to 

 mark the chronological steps in the series, to show 

 the numerous gradations by which it may have passed 

 from its rude, or accidental, or imperfect origin, to 

 the mature state in which we now behold it, and 

 from which we are incessantly deriving so many advan- 

 tages. Much, it is true, has been done in this respect, 

 but much more remains to be accomplished. The simile 

 of a bridge of numerous arches, by which human life 

 has been sometimes aptly illustrated by the moralists, 

 might, with a simple inversion, be applicable to what is 

 before us : there the whole of the bridge is seen, except 

 its extremities, which are pictured as enveloped in 

 clouds; here the extremities are illuminated, while 

 mists and fogs hang over many portions of the inter- 

 vening space. It may, however, be useful, especially to 

 the younger votaries of philosophy, to fix the attention 

 for a while upon the extremities which are most plainly 

 marked ; to contrast the appearance of the early germ 

 with that of the mature plant; to meditate upon the 

 astonishing difference between the first thought and the 

 expanded series of deductions from it, between the 

 naked, insulated propositions which were first educed, 

 and the complete system of which they at present form 

 perhaps a very inconsiderable part. Such is the object 



