168 Science, Theory and Practice. 
In regard to the spiritual and moral, I need only refer to the 
constant and sublime use in the sacred writings, of images, alle- 
gories and precepts, derived from observations of agriculture. 
It is with the intellectual we have here chiefly to do. 
Agriculture ministers to the cultivation of our higher faculties, 
from the fact, that whilst it is the means of gaining a livelihood, 
it is also an art and a science. 
Any occupation, considered with reference, not to its immediate 
and obvious object, but to the principles on which it rests, becomes 
an art. Thus husbandry, in the hands of the ignorant boor, who 
does only what he has learned from imitation, is simply a mechan- 
ical occupation. To him who is capable of viewing the principles 
on which it rests, as a whole, of giving a reason for his practice, 
based on a law, of seeing it in its relations to other occupations, 
and to man, it is an art. 
The whole body of knowledge of a subject, in other words, of 
principles verified by observations and practice, is a science. 
A reason for practice (or explanation of phenomena,) deduced 
from verified principles, is a theory. 
Thus the theory of tides, is an explanation of the phenomena 
of tides, drawn from established principles of gravity. The theory 
of the lallow, is the reason for the practice, based on acknowledged 
principles of agriculture, &c. 
Practice, is the whole body of rules and usages, existent at any 
time and place, from whatever source derived, carried out without 
reference to principles; being the mode of proceeding which the 
average common sense of mankind has authorized under the cir- 
cumstances, and experience has approved. 
It is stated in the article which I averted to in the commence- 
ment, that " practice had introduced more discoveries into Agri- 
culture, assisted by observation, than science." This is the error 
to which, as it seems to me, a confusion of terms has led. Strictly 
speaking, I do not see how either science or practice can intioduce 
a discovery. For a science is simply a body of established prin- 
ciples, and practice is nothing but the body of established usage. 
To introduce discoveries would appear to be the province of theory; 
for a theory is a reason for a practice, Avhether established or 
proposed, derived from principles, verified by observation, i. e., from 
science, and thus, if I understand the writer, his " practice as- 
sisted by observation," is only another name for that much abused 
and obnoxious thing, theory. 
There is only one other source of discovery which occurs to me, 
which is, accident. But to observe an accident accurately, to de- 
tect in it the principle which causes the particular facts to be seen 
as the universal law of similar cases, is also a species of theory. 
The ignorant man will pass by the accident, which to the man 
of science, is the foundation of a great discovery. 
