ARE SOILS ENRICHED, IMPOVERISHED, [Part III. 
Carbon, nitrogen, hydrogen, and oxygen, with 
certain peculiar inorganic or incombustible mat¬ 
ters, are the sole constituents of plants. Indeed, 
all organic existences, that is, the endless va¬ 
rieties of the animal and vegetable kingdoms, 
are composed of these four elements alone. 
These four elements are contained in carbonic 
acid, water, and ammonia. Throughout all or¬ 
ganic nature, during life, combination from the 
constituents of these three goes on, and after 
death the decomposition of those combinations 
into the constituents of these three: that is, 
carbonic acid, water, and ammonia furnish the 
constituents from which, by combination, result 
all the exquisite living forms which we admire 
and love ; and into these three those forms are 
by decomposition eventually resolved. Through¬ 
out the realms of vitality the actual living are 
the late dead freshly combined; and from the 
decomposition of one generation of plants and 
animals the recomposition of another generation 
results.* 
* Pythagoras received doctrines very similar to these 
from Egypt and India. Ovid describes them thus : — 
“ Omnia mutantur; nihil interit .... 
Haec quoque non perstant quae nos elementa vocamus .... 
— ■ tamen omnia hunt; 
Ex ipsis, et in ipsa cadunt .... 
Nec species sua cuique manet, rerumque novatrix 
Ex aliis alias reparat Natura figuras. 
