and 8 hours, the month of Peragration, there will arise 53 daies and 10 hours, which divided by 2, makes 26 daies and 22 hours: called by Physitians the medical month: introduced by _Galen_ against _Archigenes_, for the better compute of Decretory or Critical daies. [Sidenote: _What a Critical day is._] As for the Critical daies (such I mean wherein upon a decertation between the disease and nature, there ensueth a sensible alteration, either to life or death,) the reasons thereof are rather deduced from Astrology, then Arithmetick: for accounting from the beginning of the disease, and reckoning on unto the seventh day, the Moon will be in a Tetragonal or Quadrate aspect, that is, 4 signs removed from that wherein the disease began: in the fourteenth day it will be in an opposite aspect: and at the end of the third septenary, Tetragonal again: as will most graphically appear in the figures of Astrologers, especially _Lucas Gauricus_, _De diebus decretoriis_. Again, (Beside that computing by the Medical month, the first hebdomade or septenary consists of 6 daies, seventeen hours and an half, the second happeneth in 13 daies and eleven hours, and the third but in the twentieth natural day) what _Galen_ first, and _Aben-Ezra_ since observed in his Tract of Critical daies, in regard of Eccentricity and the Epicycle or lesser orb wherein it moveth, the motion of the Moon is various and unequal; whereby the Critical account must also vary. For though its middle motion be equal, and of 13 degrees, yet in the other it moveth sometimes fifteen, sometimes less then twelve. For moving in the upper part of its orb, it performeth its motion more slowly then in the lower; insomuch that being at the height, it arriveth at the Tetragonal and opposite signs sooner, and the Critical day will be in 6 and 13; and being at the lowest, the critical account will be out of the latitude of 7, nor happen before the eighth or ninth day. Which are considerations not to be neglected in the compute of decretory daies, and manifestly declare that other numbers must have a respect herein as well as 7 and fourteen.