Truth, How Determined?

What shall I liken truth unto? I will liken it unto a schoolmaster who calls his pupils around him and delivers unto them a mathematical problem, and to everyone a problem according to their several abilities, with directions how to work it out, and then goes his way. And when he returns he calls his pupils around him and inquires of them the answer. The first comes and says, Master, you delivered me this problem and here is my answer. The Master, or truth, sees that it is right and gives him the prize, and then calls on another and another till he calls the youngest of them all. Then he says, Master, you gave me too hard a problem and I could not do it; here it is. Then the truth gives the problem to one that can do it and casts the unprofitable direction into outer darkness and gives to the child another that it can understand. So everyone that understands the true directions will arrive at the truth, but he that understands it not will be misled and the evils or misery that follow are the result of the matter, and the destroying of the matter or error is the changing of the direction and the hell or misery is the name of the effect that follows our act, and the heaven or happiness is what follows the same. Therefore, we cannot serve both masters at the same time. How shall we know whose servant we are? I will give you a sign. When anyone comes and says, I know the truth, ask for proof, and if you find that it is based on an opinion, do not believe it because he says so but listen to inward answer. In this way you will steer clear of a great deal of misery.