There are some kinds of birds which live by night in the midst of darkness; others which fly by day in full light.  Bats, owls, night-ravens are birds of night:  if by chance you cannot sleep, reflect on these nocturnal birds and their peculiarities and glorify their Maker.  How is it that the nightingale is always awake when sitting on her eggs, passing the night in a continual melody? Arist., H.A. viii. 75.  Pliny x. 43.  “Luscinus diebus ac noctibus continuis quindecim garrulus sine intermissu cantus, densante se frondium germine, non in novissimum digna miratu ave.”  How is it that one animal, the bat, is at the same time quadruped and fowl?  That it is the only one of the birds to have teeth?  That it is viviparous like quadrupeds, and traverses the air, raising itself not upon wings, but upon a kind of membrane? So also Basil in Hom. on Isaiah iii. 447.  cf. Pliny x. 81, “cui et membranaceæ pinnæ uni.”  What natural love bats have for each other!  How they interlace like a chain and hang the one upon the other!  A very rare spectacle among men, who for the greater part prefer individual and private life to the union of common life.  Have not those who give themselves up to vain science the eyes of owls?  The sight of the owl, piercing during the night time, is dazzled by the splendour of the sun; thus the intelligence of these men, so keen to contemplate vanities, is blind in presence of the true light.