Two characteristics, as I have already had 5 occasion to say, are generally found to attend the history of Science: first, its instruments have an innate force, and can dispense with foreign assistance in their work; and secondly, these instruments must exist and must begin to act, 10 before subjects are found who are to profit by their action. In plainer language, the teacher is strong, not in the patronage of great men, but in the intrinsic value and attraction of what he has to communicate; and next, he must come 15 forward and advertise himself, before he can gain hearers. This I have expressed before, in saying that a great school of learning lived in demand and supply, and that the supply must be before the demand. Now, what is this but the very history 20 of the preaching of the Gospel? who but the Apostles and Evangelists went out to the ends of the earth without patron, or friend, or other external advantage which could insure their success? and again, who among the multitude they 25 enlightened would have called for their aid unless they had gone to that multitude first, and offered to it blessings which up to that moment it had not heard of? They had no commission, they had no invitation, from man; their strength lay 30 neither in their being sent, nor in their being sent for; but in the circumstances that they had that with them, a Divine message, which they knew would at once, when it was uttered, thrill through the hearts of those to whom they spoke, and make for themselves friends in any place, 5 strangers and outcasts as they were when they first came. They appealed to the secret wants and aspirations of human nature, to its laden conscience, its weariness, its desolateness, and its sense of the true and the Divine; nor did they 10 long wait for listeners and disciples, when they announced the remedy of evils which were so real.