problem with a line of a poem

0In the poem Dejection :An Ode written by S.T.Coleridge :02br
00 (missing image) Which better far were mute.02br
00 For lo ! the New-moon winter-bright !02br
01a00And overspread with phantom light02a02br
00 (With swimming phantom light o'erspread02br
00 But rimmed and circled by a silver thread)02br
01font00I see the old Moon in her lap, 00foretelling02br
02font00 00The coming-on of rain and squally blast.02br
02br
00The meaning is written with the text is like this:"the old moon in the cicular disk of the new" What does this mean? ,in fact I cant understand the fact .If someone can clarify the thing clearly I shall be obliged.0-