12 
Proceedings of Hie Royal Society 
and have no application to the case of those who have sufficient 
knowledge to enable them to avoid the possible dangers of l^ewton’s 
method : — 
I. For. Is it wise to teach a student by means of the conception 
of force, and then as it were to kick down the scaffolding by telling 
him there is no such thing ? 
II. Against. Is it wise to give up the use of a system, due to 
such an altogether exceptional genius as that of Newton, and which 
amply suffices for all practical purposes, merely because it owes part 
of its simplicity and compactness to the introduction of a concep- 
tion which, though strongly impressed on us by our muscular 
sense, corresponds to nothing objective! 
Everyone must answer these questions for himself, and his answer 
will probably be determined quite as much by his notions of the 
usefulness of the study of natural philosophy as by his own idio- 
syncrasies of thought. To some men physics is an abomination, to 
others it is something too trivial for the human intellect to waste its 
energies on. With these we do not reason. To others again all 
its principles are subjects of intuitive perception. They could have 
foreseen the nature of the physical world, and they know that it 
could not have been otherwise than they suppose it to be. Many 
minds find delight in the contemplation of the three kinds of lever ; 
others in the ingeniously disguised assumptions in Duchayla’s 
“ proof” of the parallelogram of forces ; some, perhaps, even in the 
wonderful pages of Vis Riertice Vida! _ The case of these men is 
only not more hopeless than that of the former classes because it is 
impossible that it could be so. 
But those who desire that their scientific code should be, as far 
as possible, representative of our real knowledge of objective things, 
would undoubtedly prefer to that of Newton a system in which 
there is ' not an attempt, however successful, to gain simplicity by 
the introduction of subjective impressions and the corresponding 
conceptions. 
In the present paper simplicity of principle, only, is nought for ; 
and the mathematical methods employed are those which appeared 
(independent altogether of the question of their fitness for a 
beginner) the shortest and most direct. A second part will be 
devoted to simplicity of method for elementary teaching. 
