This should be called the principle of the separation of conception from
execution, rather than by its more common name of the separation of mental
and manual labor (even though it is similar to the latter, and in practice
often identical). This is because mental labor, labor done primarily
in the brain, is also subjected to the same principle of separation of
conception from execution: mental labor is first separated from manual
labor and, as we shall see, is then itself subdivided rigorously according
to the same rule (79).