TREE-FORM OUT OP ITS UNIT. 25 



and perishable as summer leaves swept by autumnal winds 

 from the trees of the forest. It is thus that the noble tree 

 of science grows not the deadly Upas, disseminating every- 

 where poison and death, but the " Tree of Life," whose 

 " leaves are for the healing of the nations." 



We may also learn from the tree an impressive lesson of 

 our own frailty. Where are the leaves which built up this 

 massive and majestic tree, which carries in the interior of 

 its stem the monumental history of its life, the impression 

 left by centuries of seasons ? And where are the workmen 

 who felled the forests and drained the swamps of Pennsyl- 

 vania, built her cities and rail-roads, and spread over her 

 hills and valleys so many scenes of rural industry, peace, and 

 progress ? This is the work of former generations, who have 

 passed away like summer leaves from the tree which they 

 were engaged in constructing. We now supply their places, 

 and carry on their labors. We profit by the industry and 

 experience of those human generations which have preceded 

 us. Each industrious man works not only for himself, but 

 for posterity. We contribute a little during the active 

 periods of our life, to the advancement of the science and 

 civilization of society, and then we pass away and are Been 

 no more here, forever. " We all do fade as a leaf." 



