3 64 fttA GMENTS OP SCIENCE. 
question intrudes itself with resistless might, Whence 
comes the sequence? What is it that binds the consequent 
to its antecedent in nature? The truly scientific intellect 
never can attain rest until it reaches the forces by which 
the observed succession is produced. It was thus with 
Torricelli; it was thus with Newton; it is thus pre-emi- 
nently with the scientific man of to-day. In common with 
the most ignorant, he shares the belief that spring will 
succeed winter, that summer will succeed spring, that 
autumn will succeed summer, and that winter will succeed 
autumn. But he knows still further and this knowledge 
is essential to his intellectual repose that this succession, 
besides being permanent, is, under the circumstances, 
necessary; that the gravitating force exerted between the 
sun and a revolving sphere, with an axis inclined to the 
plane of its orbit, must produce the observed succession of 
the seasons. Not until this relation between forces and 
phenomena has been established, is the law of reason ren- 
dered concentric with the law of nature; and not until 
this is effected does the mind of the scientific philosopher 
rest in peace. 
The expectation of likeness, then, in the procession of 
phenomena, is not that on which the scientific mind founds 
its belief in the order of nature. If the force be perma- 
nent the phenomena are necessary, whether they resemble 
or do not resemble anything that lias gone before. Hence, 
in judging of the order of nature, our inquiries eventually 
relate to the permanence of force. From Galileo to New- 
ton, from Newton to our own time, eager eyes have been 
scanning the heavens, and clear heads have been ponder- 
ing the phenomena of the solar system. The same eyes 
and minds have been also observing, experimenting, and 
reflecting on the action of gravity at the surface of the 
earth. Nothing has occurred to indicate that the operation 
of the law has for a moment been suspended; nothing has 
ever intimated that nature has been crossed by spontaneous 
action, or that a state of things at any time existed which 
could not be rigorouslv deduced from the preceding 
state. 
Given the distribution of matter, and the forces in oper- 
ation, in the'timeof Galileo, the competent mathematician 
of that day could predict what is now occurring in our 
own. We calculate eclipses in advance, and find our cal- 
