Architect, Engineer, Contractor

An architect is said to be someone who knows a very little about a great deal and keeps knowing less and less about more and more until they know practically nothing about everything.

An engineer is someone who knows a great deal about very little and who goes along knowing more and more about less and less until finally they know practically everything about nothing.

A contractor starts out knowing practically everything about everything, but ends up knowing nothing about anything due to their association with architects and engineers.