LETTER XXL 
TIME, abftraftedly confidered, inde- 
pendant of vifible motion, is lefs dif- 
ficult to conceive than to explain or define. 
The Ariftotelians made fad nonfenfe of their 
xlefinition of Time mime rus motus fecundum 
prius et pqfterius. Bat though we cannot 
eafily explain our idea of abfolute Time, 
what we mean by relative Time, may be 
communicated with great facility. The an- 
nual and diurnal motions of the Earth are 
performed in certain fixed portions of ab- 
folute Time: thefe portions therefore may 
be divided and fubdivided into months, 
weeks, days, hours, minutes and fecondsj 
which feconds are diftinctly marked by the 
fwing of a pendulum of a certain length. 
Some attempts have been made to apply 
thefe regular ofcillations of pendulums to 
mufical Time, fo as to determine the abfo- 
lute duration or length of each note. It 
was an idle project, becaufe it were ufelefs 
and impracticable. 
Mufical Time is merely relative, and muft 
always be arbitrary. It depends on the 
flue- 
