"I have to suspend my brain and mingle the subtle essence of my mind with this air..."

"... which is of the like nature, in order clearly to penetrate the things of heaven. I should have discovered nothing, had I remained on the ground to consider from below the things that are above; for the earth by its force attracts the sap of the mind to itself. It's just the same with the watercress."

Socrates, in "The Clouds," by Aristophanes.