Exchange, [218]alternate as they glide athwart
The brazen threshold vast. This enters, that
Forth issues; nor the two can one abode
At once constrain. This passes forth and roams
The round of earth; that in the mansion waits,
Till the due season of her travel come.
Lo! from the one the far-discerning light
Beams upon earthly dwellers; but a cloud
Of pitchy blackness veils the other round:
Pernicious Night: aye-leading in her hand