Fixt Stars are, like the S005 enobled with theiVown native 
Light, he fees no inconvenience in it to sffirm, that they 
inuftalfo be fubjefi to the incurfions of fuch Spots^as the 
SuniSj which frequently augmenting abcut thtmdo cb« 
fcure^inspairjor quite abfcond theirLighr3& rhatfcmetimes 
for alocgjfometimes for a fhorttimej&by turnsjaccerding 
as the matter^of which they are niade up^ gathers together 
in great or fmall quantity.And therefore if fuch bodies up» 
on a fudden meet about any Star^ which for many ages^be- 
ing free from fuch darkning matter,did fhine very bright to 
us, what wonder^it fhould be obfcured.or vanifh altogether? 
Agaiuj if any Star, which before had alwaies about it fuch 
a quantity of Spots, as that for a long time it was counted to 
be (for example) of the fourth Magnitude^do unexpedted- 
ly unvail itsface^it will then fhine forth and challenge pofii. 
bly the place of a Star of the fecond or firfl Magnitude 
Again, if any Star^ having been for many ages confined to 
a dark prifon among thefe Spots^do break Prifon and fbow 
its formerly reftrain*d Lightj what wonder, if there appear 
to u? a New and never before feen Star? And if by anew 
colledion of Spots it return to its former imprifonment 5 
whs^t wondeTjif we lofe again the Splendor of it ?Lafl]y5if 
one only part of the body of any Star lets our its internal 
luftre, and have a periodical motion about its own Genten 
you I fee it^no lefs than that of Bullialdus*s in the Whale^ ap. 
pear at certain determinate timesj until] a new mafs of dol- 
leded Spots, or a new Opening of the fame do oecafion an 
unexped:ed alteration* 
Thefe our Author propofes as Pofjtble Caufes of fuch Efi 
feds 5 remitting thofe, that require Indubitable ones, to that 
ofZ«^r<2w Pharfal. L I. 
^imrite quos agitat Mundi laher ; at mihi femper 
T% quscmque moves tarn crebros Can fa meatms 
Vt Superi mlmre^ late *« ^ „ - 
So much of this Exercitatioiijwhieh we confider asmofl: 
proper for our purpofe. As for the others ^ we fhall but 
