THREE:In forming an estimate of the value of his services, an apprentice sees what his hands have performed, compares it with what a skilled man will do, and estimates accordingly, assuming that his earnings are in proportion to what has been done; but this is a mistake, and a very different standard must be assumed to arrive at the true value of such unskilled labour.When we look at a steam-engine there are certain impressions conveyed to the mind, and by these impressions we are governed in a train of reflection that follows. We may conceive of a cylinder and its details as a complete machine with independent functions, or we can conceive of it as a mechanical device for transmitting the force generated by a boiler, and this conception might be independent of, or even contrary to, specific knowledge that we at the same time possessed; hence the importance of starting with a correct idea of the boiler being, as we may say, the base of steam machinery.
We like seeing designers experimenting with the gradations between two extremes. Take wristwatches, for instance.