Our life is simply a series of combustions. Yes, our thoughts, feelings and actions, all our expressions are accompanied by combustion.
To generate energy for our life, materials must be burnt somewhere. This combustion inevitably produces residues that must be thrown away; otherwise, what would happen? If we do not clean the glass of an oil lamp, it will not give light anymore; if we do not clear away the ashes of a coal stove, it cannot give off heat.
In the same way, if humans have not learnt to rid themselves of their wastes, they sink into darkness and cold.
Unfortunately, most humans think they can do any kind of activity without taking care to eliminate impurities.
And yet they know they must wash themselves every day, otherwise the pores of their skin will be blocked, and this is detrimental to their health. Well, in the same way, they must think of washing themselves inwardly to clean the pores of their spiritual skin and thus re-establish communication with the divine world.