the waves of time

"The leaden circles dissolved in the air."

This short, recurring sentence appears whenever Big Ben strikes, and if traced across the whole book, could represent the gongs of the clock itself, the reverberations of which leave an ominous air in their wake. Big Ben's chimes are beautiful, "musical," yet they reveal something more chilling within them: that time, life is "irrevocable." 

I think the "circles" refer to man's tendency to seamlessly, subconsciously weave the tenses (past, present, future) of time into every stage of our existence. The use of the word "leaden" connotes a heaviness, a weight, a burden. Time is oppressive. It ruthlessly, stealthily flows onward, onward, eroding our life by the droplets of each second. "Leaden" also brings to mind, quite literally, a block of lead: soft, malleable, visible, perceptible. Time is not pliable yet it is fluid in nature; time is not transformable—it is the transformer; time is not physically seen yet it is discernible all around us, on us; time is imperceivable, elusive; time dissolves.

In the words of Benjamin Franklin, "Dost thou love life? Then do not squander time, for that's the stuff that life is made of." If we cannot capture or control time, the least we can do is to ride the waves with an appreciation of the beauty of every moment that is life.