P reads here:
As in the firmament
Starres by the sunne are not enlarg'd but showne
Greater; Loves deeds, &c.
This certainly makes the verse clearer. As it stands l. 18 is rather an enigma. The stars are not revealed by the sun, but hidden. Grosart's note is equally enigmatical: 'a curious phrase meaning that the stars that show in daylight are not enlarged, but showne to be brighter than their invisible neighbours, and to be comparatively brighter than they appear to be when all are seen together in the darkness of the night.' P is so carelessly written that an occasional good reading may be an old one because there is no evidence of any editing. The copyist seems to have written on without paying any attention to the sense of what he set down. Still, 'Gentle' is the reading of all the other MSS. and editions, and I do not think it is necessary or desirable to change it. But P's emendation shows what Donne meant. By 'showne' he does not mean 'revealed'—an adjectival predicate 'larger' or 'greater' must be supplied from the verb 'enlarg'd'. 'The stars at sunrise are not really made larger, but they are made to seem larger.' It is a characteristically elliptical and careless wording of a characteristically acute and vivid image. Mr. Wells has used the same phenomenon with effect:
'He peered upwards. "Look!" he said.
"What?" I asked.
"In the sky. Already. On the blackness—a little touch of blue. See! The stars seem larger. And the little ones and all those dim nebulosities we saw in empty space—they are hidden."
Swiftly, steadily the day approached us.' The first Men in the Moon. (Chap. vii. Sunrise on the Moon.)
A similar phenomenon is noted by Donne: 'A Torch in a misty night, seemeth greater then in a clear.' Sermons 50. 36. 326.