The great question with Buddha and his immediate disciples was not how Nirvana, the goal of human aspiration, was to be defined, but how it was to be attained. It was for him sufficiently expressed as the final extinction of all the roots of sorrow, and he taught that this consummation could only be reached by knowledge. Ignorance was the ultimate ground of all suffering existence, but, as in Christianity, men could know the truth, and the truth would set them free. According to both religions, this knowledge could neither be transmitted by tradition nor learned by a simple intellectual process. It implied a moral and spiritual training, and was the fruit of obedience; but there again the analogy ends, for the Buddhist’s idea of knowledge is as widely contrasted with the Christian idea as is its idea of the Truth to be known. In Christianity knowledge means Divine illumination or revelation, the result of trustful surrender to Christ, the revealer of the Father, and Himself the Truth. In Buddhism it meant a knowledge gained by man himself, through a process of moral culture and self-control.[209] In Christianity it was a grace that came through obedience to a better Will; in Buddhism it meant simply obedience to a Law. That law, moreover, had no commanding power to enforce it, and involved no moral obligation in the Christian sense to obey it. It was not a law like the law of Moses or the law of Christ, for it implied no Lawgiver to make it binding. It was simply a rule, a method, discovered by man, and followed because he found it expedient to follow it. Adopting this method, observing this rule, persevering in this course, a man would attain to knowledge of the truth of things, but this supposed truth is the very contradiction of the truth as it is in Jesus, the truth by which we are sanctified, and made wise unto salvation.[210]