Page:Principles of Political Economy Vol 1.djvu/67

Rh each use, it does not do its work by being deteriorated, as the coal and the fleece do theirs by being destroyed; on the contrary, it is the better instrument the better it resists deterioration. There are some things, rightly classed as materials, which may be used as such a second and a third time, but not while the product to which they at first contributed remains in existence. The iron which formed a tank or a set of pipes may be melted to form a plough or a steam-engine; the stones with which a house was built may be used after it is pulled down, to build another. But this cannot be done while the original product subsists; their function as materials is suspended, until the exhaustion of the first use. Not so with the things classed as implements; they may be used repeatedly for fresh work, until the time, sometimes very distant, at which they are worn out, while the work already done by them may subsist unimpaired, and when it perishes, does so by its own laws, or by casualties of its own.

The only practical difference of much importance arising from the distinction between materials and implements, is one which has attracted our attention in another case. Since materials are destroyed as such by being once used, the whole of the labour required for their production, as well as the abstinence of the person who supplied the means for carrying it on, must be remunerated from the fruits of that single use. Implements, on the contrary, being susceptible