[Of the halcyon] The halcyon is a seabird which produces its young on the shore, depositing its eggs in the sand, around midwinter. It chooses as the time to hatch its young, the period when the sea is at its highest and the waves break more fiercely than usual on the shore; with the result that the grace with which this bird is endowed shines forth the more, with the dignity of an unexpected calm. For it is a fact that when the sea has been raging, once the halcyon’s eggs have been laid, it suddenly becomes gentle, all the stormy winds subside, the strong breezes lighten, and as the wind drops, the sea lies calm, until the halcyon hatches its eggs.
The eggs take seven days to hatch, at the end of which the halcyon brings forth its young and the hatching is at an end. The halcyon takes a further seven days to feed its chicks until they begin to grow into young birds. Such a short feeding-time is nothing to marvel at, since the completion when the hatching process takes so few days.
This little bird is endowed by God with such grace that sailors know with confidence that these fourteen days will be days of fine weather and call them ‘the halcyon days’, in which there will be no period of stormy weather.