[ 739 ] 
in time, the ruin of it ; for, after the reception of 
the difdiapafon fyftem, the elementary treatifes, as 
we fee by what is left to us of them, became filled 
with this new dodtrine of the parts and relations of 
the fyftem, of its tranfpofitions, of the pofitions of 
the mefe, of founds in power, and found by pofition, 
and many other dodtrines flowing from the fame 
fource, till, in time, the fyftem itfelf came to be 
confidered as the true type of a mode ; and a 
number of new modes were introduced, that were 
grounded on no other principle than this, which I 
fcruple not to call a falfe dodtrine of them, though 
the antients admitted it for convenience, as I have 
fhewn, and thereby almoft loft their impreflions of 
the new one. 
Having thus pointed out the origin of thefe two 
dodtrines, as far as was poflible, from a general view 
of them, and without entering into a critical exami- 
nation of the many paflages of the antients, that 
might help us to greater certainty, I ihall now pro- 
ceed. 
Fifthly , To fhew how far the preceding explana- 
tions may be fupported by arguments, or war- 
ranted by the teftimony of antient writers. 
Here I muft repeat, that the harmonic dodtrine of 
the tones, as I have explained it, is found, exprefly 
delivered under its proper head, in almoft every 
writer on the fubjedt; and that the dodtrine of the 
fpecies of diapafon is found alfo in the harmonic 
treatifes, though not under the head of tones, nor ex- 
prefly applied to them. Now, this being the cafe, 
I lhall have no occafion to wafte time in bringing 
Vol. LI. 5 C particular 
