Truth

“A man’s mind falls ill when he relinquishes his hold on truth—not by lying, though he lie often, for in that case the injury to the spirit can be repaired by contrition and the renewal of good will—but by an inward revolt from truth. True illness of the mind and spirit sets in when a man no longer cherishes truth but despises it, when he uses it as a means to his own ends, when in the depths of his soul truth ceases to be to him the primary, the most important concern.”
~Romano Guardini