What are the links between natural jobs, labor and slavery?

According to George Bernard Shaw there are links between natural jobs, labor and slavery because natural jobs can be slavery in their context we are doing natural jobs to earn a living for that we are using other living beings as our slaves and we are also the slaves of the masters who provide us the job and he will be a slave of some others and this cycle continues in the society therefore there is a link between natural job, labor and slavery.