Village and town clocks also chimed on the hour. In days when light was scarce, the audible telling of time was important, hence the use of repeater clocks which, when a button was pressed, or a string pulled, chimed out the hour most recently passed. Tells = gives an account of, speaks (by chiming). That tells the time, count = record, sum up The overall effect is sombre, and the concluding couplet, with its brave stand against time, confined to a single line in the poem, gives the impression that nothing will be saved, and that the reality of what the poet has been urging all along is as slight as breath and water. The significance of the placing of this sonnet here (12) (twelve hours of the day) as well as that of the 'minute' sonnet at 60 is difficult to determine, but at the very least it points to an ordering hand, which, like the clock itself, metes out the sequence of relevant events as they occur. The way in which the sense of the lines ends with the line itself is like the ticking of a clock or the inexorable motion of a pendulum as it beats from side to side. The slow and swift passage of time which brings all things to an end is described, not indeed copiously, but with such significant and devastating effect that mortality almost stares us in the face as we read it.
It will always be one of the finest sonnets in the history of language. This sonnet is so famous that it almost makes comment superfluous.