Planning and doing

Planning and doing are separate parts of the same job; they are not separate jobs.  There is no work that can be performed effectively unless it contains elements of both.  One cannot plan exclusively all the time.  There must be at least a trace of doing in one's job.  Otherwise one dreams rather than performs.  One cannot, above all, do only; without a trace of planning his job, the worker does not have the control he needs even for the most mechanical and repetitive routine chore.  Advocating the divorce of the two is like demanding that swallowing food and digesting it be carried out in separate bodies.

Peter Drucker (1954) "The practice of management" Harper business edition, p284.