Contrast will help us a little here. Commodities can always be measured by some _Standard_ outside of themselves: for example, land-parcels are measured into acres and fractions thereof by a surveyor's compass and chain; metals and cereals are weighed into centners and parts thereof by scales of some sort; and sugar is not only weighed at the custom-house, but tested as to other qualities by the polariscope. Now land, wheat, sugar, and all other commodities, have an existence separate from the standards that measure them, and whether they are bought or not they continue for a time essentially the same. They exist _per se_. They were indeed brought into existence on purpose to be sold, and if they cannot be sold, similar things additional will not then and there be brought into the market, but these things themselves are there separate from the seller and separate from the buyer. Not so with personal services. They do not exist _per se_. They are not separate from the seller, and they cannot come into existence without a buyer. _Skill_ is something the artisan cannot part with, nor can he sell the service to which the skill gives rise till the buyer be present with the return-service in his hands. The Laborer of any class cannot put his "service" on exhibition, and then wait for a buyer, as the commercial drummer sells goods by sample. The doctor, for example, must have his _patient_ before he can show his skill. The buying and selling of personal services, accordingly, is more intimate and ultimate than the buying and selling of commodities: it brings people more closely together: it depends much more on traits of _character_ and on acquired _skill_.