Imagine you're sitting in a cave for a very long time, not days, weeks but thousands of years. It's very, very quiet and all you can hear are the droplets of water on the floor below.
As time goes by the calcite in the water begins to form stalactites on the roof above (top down) and stalagmites on the floor below (bottom up).
Over time both begin to grow slowly, but the stalactites grow quicker due to their hollow straw like structure. The stalagmites however are slower to form because they are solid inside. The base of the stalactites tend to be smaller due to the weight they have to carry and they often break off and start again, where as the stalagmites bases are larger, stronger and therefore more stable
Stalactites can be compared to a top down driven culture, where leaders tend to set the tone of the culture and build systems and procedures that they think the workforce should adopt. They then try and cojole the workers to use them with safety briefings, toolbox talks, permits to work etc, etc. All seems to go well, until the paperwork becomes overpowering (top heavy) or the charismatic leader leaves or dies and the system falls apart.
Stalagmites can be compared to a bottom up culture, where the workers are nurtured from above (the dripping calcite) and empowered to build the very culture they want to adopt. As time goes by, the stable culture grows steadily outward at the base influencing more people and steadily climbs upward towards its goal (Utopia), although this might take thousands of years to create.