But when my glass shows me myself indeed, Beated and chopp'd with tann'd antiquity, 62. And more, much more, than in my verse can sit Your own glass shows you when you look in it. The beauties it shows do not last, and beauty itself is not to be trusted. Here in this sonnet also some of that idea is present, for the glass is beginning to show lines and wrinkles, hints of old age and of mortality. It is better to have the pun the other way round.
Beauty wears out and decays as clothes and other artifacts wear out and decay.
Thy sundial' and the other descriptions of looking in a glass suggest private possession of those things, and private meditation. A pocket sundial would be rather difficult to use, as one would need to know in advance in which direction to point it. However shady stealth of line 7 seems to lean more towards a sundial, as the gnomon casts a shadow from which the time was told. But a clock with its insistent ticking never ceases to tell one how the precious minutes go to nothing. The vacant leaves thy mind's imprint will bear, 3.