I just happened across this paper which caught my attention. http://hdl.handle.net/2027.42/7869 Perhaps this has been discussed here before, but it's new to me and I have learned from several of these books. What is the correct use or intepration of [itex]\nabla[/itex] and it's use in the 'div' and 'curl'? What textbooks do contain the correct use? Apparently "Mathematics of Classical and Quantum Physics", by Byron and Fuller, does give an appropriate treament, since if refers to gradient, div and curl as differential operators, and [itex]\nabla[/itex] is referred to as an operator ei[itex]\partial_i[/itex]. Byron and Fuller explicitly mention that [nabla] is an operator and should not be thought of a vector.