Fourthly: The experience of one age differs from that of another. That which lies outside the experience of one century becomes within the experience of the next. The truth is that the sum of human experience is receiving continual additions, in proportion as the sphere of observation enlarges. If it is true that we ought to reject everything contrary to experience, it follows that if many of the inventions of the present age had been reported in a previous one, they ought to have been rejected as incredible. For example: if a century ago it had been affirmed that a message had actually been conveyed one thousand miles in five minutes, the assertion ought on this principle to have been rejected as contrary to the universal experience of mankind. In an earlier age, no miracle could have been more difficult to believe. Yet although contrary to prior experience, it has been established as a fact. The principle, therefore, as laid down by Hume, leads to an absurd conclusion. Fifthly: The experience of each individual is limited by his own observation and what he has learned respecting that of others. This constitutes as far as he is concerned the experience of mankind. Now, under the Equator the experience of man is that each day and night is twelve hours long. Neither he, nor his ancestors, nor any person whom he trusts, have ever had any other experience than this. To him, therefore, the affirmation that there is a place on the earth where each day and night is six months long, is contrary to experience, and ought to be rejected as a fable. Sixthly: If we confine experience to scientific experience, extraordinary discoveries are made and facts established in one age which are contrary to that of a former one. On this principle, the ground on which Herodotus rejected the story of the Phœnician navigators that they had sailed round Africa was satisfactory. It was contrary to his experience that they should have seen the sun in the position in which they affirmed that they had seen it, though it is not contrary to ours. Seventhly: Miracles viewed as mere _phenomena_ stand on exactly the same ground as very unusual occurrences, or very wonderful discoveries. As far as they are contrary to past experience, they are alike credible or incredible. They are events of which the cause is unknown, but may or may not hereafter be discovered. It is quite true that any extraordinary phenomenon requires a stronger testimony to render it credible than an ordinary occurrence. But this involves no question of abstract possibility or impossibility, but is one purely of evidence, each case having to be decided on its own merits. It must be carefully observed that when we affirm that this or that matter lies within human knowledge, or is contrary to it, experience has to do with phenomena alone. All questions of causation lie entirely beyond its cognizance.