80 ESSAYS. 
guide ; —the more so in this case, as our ordinary conceptions 
on the subject spring from a false analogy, which we have 
unconsciously established, between plants and animals. This 
common analogy might, perhaps, hold good, if the tree were 
actually formed like the animal, all the parts of which are 
created at once in their rudimentary state, and soon attain 
their fullest development, so that the functions are carried on, 
throughout life, in the same set of organs. If this were the 
case with the tree, it would likewise die, sooner or later, of 
old age, — would perish from causes strictly analogous to 
those which fix a natural limit to the life of animals. The 
unavoidable induration and incrustation of its cells and ves- 
sels, apart from other causes, would put an early and sure 
limit to the life of the tree, just as it does in fact terminate 
the existence of the leaf, the proper emblem of mortality, — 
which, although it generally liveg only a single season, may 
yet truly be said to die of old age. But, as the leaves are 
necessarily renewed every year, so also are the other essential 
organs of the plant. The tree is gradually developed by the 
successive addition of new parts. It annually renews not 
only its buds and leaves, but its wood and its roots; every- 
thing, indeed, that is concerned in its life and growth. Thus, 
like the fabled Auson, being restored from the decrepitude of 
age to the bloom of early youth, — the most recent branchlets 
being placed, by means of the latest layer of wood, in favor- 
able communication with the newly formed roots, and these 
extending at a corresponding rate into fresh soil, — 
“ Quae quantum vertice ad auras 
/Etherias, tantum radice in Tartara tendit,” 
why has not the tree all the conditions of existence in the 
thousandth, that it possessed in the hundredth, or the tenth, 
year of its age? The old and central part of the trunk may, 
indeed, decay; but this is of little moment, so long as new 
layers are regularly formed at the circumference. The tree 
survives ; and it is difficult to show that it is liable to death 
from old age in any proper sense of the term. Nor do we 
arrive at a different conclusion when we contemplate the 
tree under a less familiar but more philosophical aspect, — 
