Chapter 3, entitled “Which Came First?”, goes over a number of examples of engineering achievements that were accomplished without full scientific understanding or explanation of the phenomena involved. Among those examples are rockets, which preceded rocket science; the steam engine, which preceded thermodynamics; powered flight, which preceded a fully formed science of aerodynamics; and hybridization, which preceded genetics.Such examples—and the implications they have for the way the world really works—should lead the general reader to a fuller understanding of the nature and practice of science and engineering. I hope that they will be encouraging to inventors and engineers who wish to pursue a goal even in the absence of full scientific support for their idea.The larger context of The Essential Engineer is its relevance to the world of public policy and legislation.Since so much of what is considered by lawmakers today is necessarily technological at heart, there is great value in a book laying out clear distinctions between science and engineering and their relationship to the important political and economic goals of innovation and global competitiveness. Legislation intended to promote and support innovation, for example, may have just the opposite effect if it encourages only science, at the expense of engineering, and this should be emphasized to political leaders and lawmakers.Unfortunately, the distinct endeavors of engineering, invention, and technology are often subsumed under the single rubric “science” and so are not highlighted in their own right. This lack of attention to the true sources of innovation can jeopardize our nation’s future. The Essential Engineer is one attempt to correct this situation.