Take an instance of this economy. Suppose a man travelled from London to Oxford, then to Exeter, then to Portsmouth, then to Brighton, and afterwards desired to return to London. If he, acting on a mistaken conception of truth and disdaining instruction from others, persisted in remembering the objects perceived on his journey as--what they no doubt literally were--a continuous series, he would be unable to imagine any way of returning to London except by reversing the order of his journey. If on the other hand he carried in his mind an image of the ground in question, with the mutual position of the places, it would enable him to _foresee_ that London was to be reached by journeying northward from Brighton, in far less time and at far less cost than by returning the way he came. Thus does conceptual position, when it is correctly imagined, prove its superiority to the order of experience. And we say that the ideal picture is truer than the crude memory,--not that it is really so if natural order is a test of truth, but because it is the least onerous, which is our practical standard of truth. The only object of knowledge being the wise management of energy, that sort of knowledge must be considered truest that enables us to have the feelings we desire at the least cost. In one sense truth means the quickest and easiest way of passing from one state of consciousness to another preconceived state. It may be objected to the above example as a valid deduction from an imaginary synthesis, that the relation of London to Brighton is now a certainty, whereas an inference can be no more than a probability. The reply is, that if a man has already traversed the route in question, it is to him an actual experience and his idea of it is ever afterwards a memory, not an inference. But until it is actually perceived it must be imaginary, and therefore slightly problematical. Although a man is convinced that others are not deceiving him in saying a place is to be reached in a certain way, he cannot be absolutely sure that he fully understands the directions given, in other words, that his image of the route corresponds to their perception of it. There probably never is exact similarity between one man's primary experience and another man's idea of it. It may even be doubted whether there is ever exact similarity between a man's own primary experience and his subsequent idea of it. The geographical synthesis is founded on actual exploration supplemented by inference. The mutual position of some important places are determined and serve as precedents for a multitude of minor positional deductions. _A_ is twenty miles north of London, _B_ is ten miles south of London, hence _A_ is thirty miles north of _B_. The mileage is determined by imagining the synthesis developed into natural groups and measured laterally. Other scales are the time spent in travelling between the places, or the money it costs, or the distance delineated on a map.