Humanity needs practical men, who get the most out of their work, and, without forgetting the general good, safeguard their own interests. But humanity also needs dreamers, for whom the disinterested development of an enterprise is so captivating that it becomes impossible for them to devote their care to their own material profit.
"Astrophysics of the Diffuse Universe". Book by Michael A. Dopita and Ralph S. Sutherland, 2003.