Fortunately, however, there is a little bit of the inventor in most engineers, and a trace of the engineer in most inventors; while in some inventors there is a good deal of the engineer.

And once in a while we meet a man who carries both natures in his brain.

That man does marvels.
Despite the great gulf normally fixed, however, between the engineer and the inventor, most of the definite progress of the world for the past one hundred years has been done by the co-ordination of the two; a co-ordination accomplished by "the man of business." Now the inventor and engineer type do not exist only in the world of engineering and mechanics, though it is in that world that they are the most clearly recognized; for they exist in all walks of life.

In literature, inventors write novels; in business life, they project railroads; in strategy, they map out new lines of effort.

In literature, the engineer writes cyclopaedias; in business, he makes the projected railroads a success; in strategy, he works out logistics and does the quantitative work.
In that part of strategy of which we are now thinking--the designing of the naval machine--the inventor and the engineer clearly have two separate lines of work: one line the conceiving, and the other line the constructing, of strategic and tactical methods, and of material instruments to carry out those methods.