From this was developed, under the influence of medieval religious teaching, the meaning innocent, harmless, simple; and from this again our modern meaning, foolish, simple in a derogatory sense.

Chaucer has the word in all these meanings, and also in another, a modification of the second--wretched, pitiable.

Another shade of the same meaning appears in Spenser's "silly bark," i.e._frail_ ship, and in Burns's "To a Mouse": "Thy wee bit housie, too, in ruin! Its silly wa's the win's are strewin'!" "The epithet may be due either to the gush of love that has filled the Mariner's heart, or to his noticing the buckets, long useless, frail, now filled with water" (Sykes); very likely to both together.
14, 314--*fire-flags*.

The notion of the "fire-flags" "hurried about" was probably suggested to Coleridge by the description of the Northern Lights (_aurora borealis_) in Hearne's "Journey ...

to the Northern Ocean," a book printed in 1795 and known to both Wordsworth and Coleridge before 1798.