and [2987]Marsilius Cognatus puts Venus one of the five mortal enemies of a student:  “it consumes the spirits, and weakeneth the brain.”  Halyabbas the Arabian, 5.  Theor. cap. 36. and Jason Pratensis make it the fountain of most diseases, [2988]"but most pernicious to them who are cold and dry:”  a melancholy man must not meddle with it, but in some cases.  Plutarch in his book de san. tuend. accounts of it as one of the three principal signs and preservers of health, temperance in this kind:  [2989]"to rise with an appetite, to be ready to work, and abstain from venery,” tria saluberrima, are three most healthful things.  We see their opposites how pernicious they are to mankind, as to all other creatures they bring death, and many feral diseases:  Immodicis brevis est aetas et rara senectus.  Aristotle gives instance in sparrows, which are parum vivaces ob salacitatem, [2990]short lived because of their salacity, which is very frequent, as Scoppius in Priapus will better inform you.  The extremes being both bad, [2991]the medium is to be kept, which cannot easily be determined.  Some are better able to sustain, such as are hot and moist, phlegmatic, as Hippocrates insinuateth, some strong and lusty, well fed like [2992]Hercules, [2993] Proculus the emperor, lusty Laurence, [2994]_prostibulum faeminae Messalina_ the empress, that by philters, and such kind of lascivious meats, use all means to [2995]enable themselves:  and brag of it in the end, confodi multas enim, occidi vero paucas per ventrem vidisti, as that Spanish [2996]Celestina merrily said:  others impotent, of a cold and dry constitution, cannot sustain those gymnics without great hurt done to their own bodies, of which number (though they be very prone to it) are melancholy men for the most part.

MEMB.  III.
Air rectified.  With a digression of the Air.

As a long-winged hawk, when he is first whistled off the fist, mounts aloft, and for his pleasure fetcheth many a circuit in the air, still soaring higher and higher, till he be come to his full pitch, and in the end when the game is sprung, comes down amain, and stoops upon a sudden:  so will I, having now come at last into these ample fields of air, wherein I may freely expatiate and exercise myself for my recreation, awhile rove, wander round about the world, mount aloft to those ethereal orbs and celestial spheres, and so descend to my former elements again.  In which progress I will first see whether that relation of the friar of [2997] Oxford be true, concerning those northern parts under the pole (if I meet obiter with the wandering Jew, Elias Artifex, or Lucian’s Icaromenippus, they shall be my guides) whether there be such 4.  Euripes, and a great rock of loadstones, which may cause the needle in the compass still to bend that way, and what should be the true cause of the variation of the compass, [2998]is it a magnetical rock, or the pole-star, as Cardan will;