We who are so habituated to the employment of metal, either in the manufacture or the composition of every article which meets our eye, can scarcely realize that man lived long ages on the earth before the metals and minerals, its hidden treasures, were revealed to him. This pen I write with is of metal, or, were it a quill, it would still have been shaped by the use of steel; the rags of which this paper is made up have been first cut by metal knives, then bleached by a mineral (chlorine), then torn on a metal cylinder, then thrown into a vat which was either itself of metal or had been shaped by metal tools, then drawn on a _wire_-cloth, etc. And so it is with everything which is made nowadays. We can scarcely think of any single manufacture in which is not traceable the paramount influence of man’s discoveries beneath the surface of the ground. But primitive man could profit by no such inherited knowledge, and had only begun to acquire some powers which he could transmit to his own descendants. For his tools he must look to the surface of the earth only; and the hardest substances he could find were stones. Not only during the period of which we are now speaking, but for hundreds, perhaps thousands, of years lasted man’s ignorance of the metals, ignorance therefore of all that the metals could produce for him. The long age of this state of ignorance is distinguished in pre-history by the name of the Stone Age, because the hardest things then known to mankind were stones, and the most important of his implements and utensils had therefore to be made of stones. There can be no harm if we so far anticipate our second chapter as to say that this Stone Age is distinguished by pre-historic students into two main periods: (1) the age in which all the stone implements were made exclusively by chipping, (2) the age in which grinding or polishing was brought in to supplement the use of chipping. Wherefore the first age is also called the Unpolished Stone Age, the second is called the Polished Stone Age. Not that by any means all the implements in the later age were made of polished stone; far from it. Only that, contemporaneously with the stone implements still made by chipping merely, others of polished stone were used. But of this more hereafter. Lastly, the two epochs are also distinguished more simply as the Old Stone Age and the New Stone Age--or, turned into Greek, the Palæolithic Era and the Neolithic Era.