The beginning of most inventions is very remote. The first idea, born within some unknown brain, passes thence into others, and at last comes forth complete, after a parturition, it may be, of centuries. One starts the idea, another developes it, and so on progressively until at last it is elaborated and worked out in practice; but the first not less than the last is entitled to his share in the merit of the invention, were it only possible to measure and apportion it duly. Sometimes a great original mind strikes upon some new vein of hidden power, and gives a powerful impulse to the inventive faculties of man, which lasts through generations. More frequently, however, inventions are not entirely new, but modifications of contrivances previously known, though to a few, and not yet brought into practical use. Glancing back over the history of mechanism, we occasionally see an invention seemingly full born, when suddenly it drops out of sight, and we hear no more of it for centuries. It is taken up de novo by some inventor, stimulated by the needs of his time, and falling again upon the track, he recovers the old footmarks, follows them up, and completes the work. There is also such a thing as inventions being born before their time--the advanced mind of one generation projecting that which cannot be executed for want of the requisite means; but in due process of time, when mechanism has got abreast of the original idea, it is at length carried out; and thus it is that modern inventors are enabled to effect many objects which their predecessors had tried in vain to accomplish. As Louis Napoleon has said, "Inventions born before their time must remain useless until the level of common intellects rises to comprehend them." For this reason, misfortune is often the lot of the inventor before his time, though glory and profit may belong to his successors. Hence the gift of inventing not unfrequently involves a yoke of sorrow. Many of the greatest inventors have lived neglected and died unrequited, before their merits could be recognised and estimated. Even if they succeed, they often raise up hosts of enemies in the persons whose methods they propose to supersede. Envy, malice, and detraction meet them in all their forms; they are assailed by combinations of rich and unscrupulous persons to wrest from them the profits of their ingenuity; and last and worst of all, the successful inventor often finds his claims to originality decried, and himself branded as a copyist and a pirate.