_Accident_ is thought to be the fruitful source of great inventions. It is a factor that cannot be ignored. But accidents are only occasional helps, rarely occurring,--flashes of light suddenly revealing the end of the path along which the inventor has been painfully toiling, and unnoticed except by him alone. They are sudden discoveries which for the most part simply shorten his journey. The rare complete contrivance revealed by accident is not an invention at all, but a discovery. The greatest incentive in modern times to the production of inventions is governmental protection. When governments began to recognize the right of property in inventions, and to devise and enforce means by which their author should hold and enjoy the same, as he holds his land, his house, or his horse, then inventions sprung forth as from a great unsealed fountain. This principle first found recognition in England in 1623, when parliament, stung by the abuse of the royal prerogative in the grant of exclusive personal privileges that served to crush the growth of inventions and not to multiply them, by its celebrated Statute of Monopolies, abolished all such privileges, but excepted from its provisions the grant of patents “for the sole working or making of any manner of new manufactures within this realm to the true and first inventor” thereof. This statute had little force, however, in encouraging and protecting inventors until the next century, and until after the great inventions of Arkwright in spinning and James Watt in steam-engines had been invaded, and the attention of the courts called more seriously thereby to the property rights of inventors, and to the necessity of a liberal exposition of the law and its proper enforcement. Then followed in 1789 the incorporation of that famous provision in the Constitution of the United States, declaring that Congress shall have the power “To promote the progress of science and useful arts by securing for limited times to authors and inventors the exclusive right to their respective writings and discoveries.” In 1791 followed the law of the National Assembly of France for the protection of new inventions, setting forth in the preamble, among other things, “that not to regard an industrial invention as the property of its author would be to attack the essential rights of man.” These fundamental principles have since been adopted and incorporated in their laws by all the nations of the earth.