Is scientific research worth doing only if it serves an obviously "useful" purpose? Kepler thought not:

For has not the all-merciful Creator ... given every creature all it needs, and beauty and pleasure beyond in over-flowing measure? ... we do not ask for what useful purpose birds do sing, for song is their pleasure since they were created for singing. Similarly we ought not to ask why the human mind troubles to fathom the secrets of the heavens. Our Creator has added mind to our senses not simply so that man might earn his daily keep ... but also so that ... we might delve into the causes of their being and becoming, even if this might serve no further useful purpose.

That was from the dedication of the Mysterium Cosmographicum. With thanks to Denis Alexander for supplying the quote, which was included in his talk at the Christians in Science conference on Saturday (30 October 2010).