Time is to clock as mind is to brain. 

The clock or watch somehow contains the time.  And yet time refuses to be bottled up like a genie stuffed into a lamp.  Whether it flows as sand or turns on wheels within wheels, time escapes irretrievably, even while we watch.

Even when the bulbs of the hourglass shatter, when darkness withholds the shadow from the sundial, when the mainspring winds down so far that the clock’s hands hold still as death, time itself keeps on.

The most that we can hope a watch to do is mark that progress. 
And since time sets its own tempo, like a heartbeat or an ebb tide, timepieces don’t really keep time. 
They just keep up with it if they’re able.

Dava Sobel.