"So, then," I said to the Master,"it is perfectly clear that the person who tells the truth is in the right, and the person who lies is in the wrong."
"Yes, it is so," replied the Master, "but this matter is more complicated than you believe it to be."
"What do you mean?" I asked.
"Imagine the man who lies all of the time. One would consider him evil, correct?"
"Yes, of course," I responded.
"But, consider this: that the man who lies all the time is, in a fashion, telling the truth."
"How can this be?"
The Master smiled. "If you were to travel with a man who lied every word, and he were giving you directions, at first you would get completely lost. After a while, though, you would realize that he was always lying to you, and when he said 'Turn left,' you would turn right, and when he said, 'Go south,' you would go north. So it would be that, in knowing him to be an incorrigible liar, you would discern the truth, and you would arrive at your destination.
"No, the man who lies every word is not nearly as dangerous as the man who tells only half a truth. For the half-liar can never be divined; he cannot be discounted, nor can he be believed. Even worse, he taints the truth by mixing truth with lies. Truth and lie are like two pigments: once mixed, the two become a different color altogether, a color not to be believed nor to be disbelieved.
"So it is that the man who tells the truth some of the time and lies some of the time is much more treacherous than the incorrigible liar. The wise can co-exist with the liar, but the man of the half-truth is death to wisdom."