Read the poem and answer the question. "an hymn to the evening" soon as the sun forsook the eastern main, the pealing thunder shook the heav'nly plain: majestic grandeur! from the zephyr's wing exhales the incense of the blooming spring. soft purl the streams; the birds renew their notes, and through the air their mingled music floats. through all the heav'ns what beauteous dies are spread! but the west glories in the deepest red: so may our breasts with ev'ry virtue glow, the living temples of our god below. fill'd with the praise of him who gives the light and draws the sable curtains of the night, let placid slumbers sooth each weary mind at morn to wake more heav'nly, more refin'd; so shall the labours of the day begin more pure, more guarded from the snares of sin. night's leaden sceptre seals my drowsy eyes; then cease, my song, till fair aurora rise. what does the word sable mean in line 12?
dark
fur
gloomy
thick