(b) There is one vital distinction to be made at the outset and held to throughout the discussion, namely, that, between all lands as a _physical thing_, which God made and gave to all men in common without any effort of their own, and some lands now as a _valuable thing_, in all probability made such through the action of human desires and human efforts brought to bear upon what _was_ merely physical but what has now _become_ valuable. The failure to distinguish between _lands_ as such and _valuable lands_ as such, has always wrought confusion and mischief in the land problem. The two things are utterly different and incommensurable. There are vast stretches of lands on the surface of the earth, to which no _value_ ever attached or ever will attach. They are lands, and that is all. Political Economy has nothing to say of them, and nothing to do with them. Because they are never bought or sold, because they never give birth to "produce," they lie wholly outside the field of Value. Then there are immense areas of lands now valuable, that were once as valueless as the first class. With these Political Economy has a great deal to do, and also with the way in which they passed from valueless to valuable. Then there is a third class of lands, that have not yet been studied as they ought and till recently have not been studied at all, namely, those known to have been valuable at one time, but which have now lost their value either wholly or in large measure. There are such lands as these in every State of our Union, and in every civilized country beneath the sun; and Political Economy has already learned something, and is destined to learn much more, about the processes by which lands pass from out the first great class into the second, and from the second into the third. Valueless, Valuable, Unvalued,--these three words describe to the economist all the lands of the world.