They exploited known scientific principles, and, if necessary, created new knowledge. Through a variety of actions, engineers created wealth that enabled the emergence of music, painting, sculpture, and literature. And they continue to do so. Much of modern medicine, all of modern transportation and entertainment are due to engineers. Even athletes exploit feats of engineering to run longer, jump higher, and lift more.
Engineering is syncretic and, therefore, multidisciplinary.
A product or a process cannot be designed with principles rooted in just one specific discipline. An electricity generation plant cannot be built by those who know electrical circuits exclusively. Every issue has to be analyzed from perspectives emanating from several disciplines. All perspectives must fit together like the pieces of a jigsaw puzzle. In a technologically advanced society, every adult should be as familiar with the circuit of a flashlight as with the themes of Ernest Hemingway's writing.