On such and such a date any neighbour would have given the owner of the horse from 20 to 25 sacks of wheat for it, or, say, 10 sheep, or 50 loads of cut wood. But suppose there comes a great mortality among horses, so that very few are left. There is an eager desire to get hold of those that survive in order that the work may be done on the farms. Then the neighbours will be willing to give the owner of the horse much more than 20 or 25 sacks of wheat for it. They may offer as much as 50 sacks, or 20 sheep, or 100 loads of wood. Yet the horse is exactly the same horse it was before. The wealth of the master has increased. His horse, as we say, is “worth more.” _It is this_ WORTH, _that is, this ability to get other wealth in exchange, which constitutes true Economic Wealth_. I have told you that the idea is very difficult to seize, and that you will find the hardest part of the study here, at the beginning. There is no way of making it plainer. One has no choice but to master the idea and make oneself familiar with it, difficult as it is. _Wealth does not reside in the objects we possess, but in the economic values attaching to those objects._ We talk of a man’s wealth or a nation’s wealth, or the wealth of the whole world, and we think at once, of course, of a lot of material things: houses and ships, and pictures and furniture, and food and all the rest of it. But the economic wealth which it is our business to study is not identical with those _things_. Wealth is the sum total of the _values_ attaching to those things. That is the first and most important point. Here is the second: Wealth, for the purposes of economic study, _is confined to those values attaching to material objects through the action of man, which values can be exchanged for other values_. I will explain what that sentence means. Here is a mountain country where there are few people and plenty of water everywhere. That water does not form part of the Economic _wealth_ of anyone living there. Everyone is the better off for the water, but no one has _wealth_ in it. The water they have is absolutely necessary to life, but no man will give anything for it because any man can get it for himself. It has no _value in exchange_. But in a town to which water has to be brought at great expense of effort, and where the amount is limited, it acquires a value in exchange, that is, people cannot get it without offering something for it. That is why we say that in a modern town water forms part of _Economic Wealth_, while in the country it usually does not.