Hourglass

Everyone knows what the hourglass means, but they don't understand it is like the Freemasons. The main meaning of this symbol is -  this is the eternal flow of time , "The sand slips away until it is no more, and therefore a constant reminder that life is finite and therefore we must make the most of it while we can."

But it also acts as an analogy between the top and the bottom, and the need to turn the hourglass from top to bottom from time to time to continue the process symbolizes the continuous cycle between life and death and heaven and earth.