Don't be 'practical' in politics. To be practical in that sense means that you have schooled yourself to think along the lines, and in the grooves that those who rob you would desire you to think.

-Connolly,James
  Socialism Made Easy.

Whoever, in the pursuit of science, seeks after immediate practical utility may rest assured that he seeks in vain.

-Helmholtz, Hermann Ludwig Ferdinand von
  Lecture at Heidelberg, collected in Popular Lectures on Scientific Subjects (1873).

   Totakeanalmost religiousview, thisearthisnothing very special.There have probably been millions of earths just like ours each producing a particular intelligent species. That isnottosay thattheyall developed well, thattheyall achieved some sort of perfection. And if the planner made lots of them and some of them chose to destroy themselves,thenwe canonlysupposethattheplanner is a hard and practical man.

-Hoyle, Sir Fred
  In the Daily Mail.

The theory of our modern technic shows that nothing is as practical as the theory.

-Oppenheimer,J(ulius) Robert
  In Reflex,  Jul.

   The instinct of mankind warns it against accepting at their face value spiritual demands that cannot satisfy themselves by practical achievements. The road along which the organized workers, like any other class, must climb to power starts from the provision of a more effective economic service than their masters, as their grip upon industry becomes increasingly vacillating and uncertain, are able to supply.

-Tawney, R(ichard) H(enry)
  TheAcquisitive Society.

Facts are generally overesteemed. For most practical purposes, a thing is what men think it is.When they judged the earth flat, it was flat. As long as men thought slavery tolerable, it was tolerable.We live down here among shadows, shadows among shadows.

-Updike,John Hoyer
  Buchanan. Buchanan Dying, act1.

   I thought it might have a practical use in something like neon signs.

-Urey, Harold Clayton
c.1934  Recalling his1932 discovery of heavy water which proved critical to the development of the atomic bomb.

He or she isgreatest who contributes the greatest original practical example.

-Whitman,Walt(er)
  Leaves of Grass,'By Blue Ontario's Shores', section13.