Slave labor has seldom been made profitable where it has been wholly employed in grazing and grain growing; but it becomes remunerative in proportion as the planters can devote their attention to cotton, sugar, rice, or tobacco. To render Southern slavery profitable in the highest degree, therefore, the slaves must be employed upon some one of these articles, and be sustained by a supply of food and draught animals from Northern agriculturists; and before the planter's supplies are complete, to these must be added cotton gins, implements of husbandry, furniture, and tools, from Northern mechanics. This is a point of the utmost moment, and must be considered more at length. It has long been a vital question to the success of the slaveholder, to know how he could render the labor of his slaves the most profitable. The grain growing States had to emancipate their slaves, to rid themselves of a profitless system. The cotton-growing States, ever after the invention of the cotton gin, had found the production of that staple highly remunerative. The logical conclusion, from these different results, was, that the less provisions, and the more cotton grown by the planter, the greater would be his profits. This must be noted with special care. _Markets_ for the surplus products of the farmer of the North, were equally as important to him as the supply of _Provisions_ was to the planter. But the planter, to be eminently successful, must purchase his supplies at the lowest possible prices; while the farmer, to secure his prosperity, must sell his products at the highest possible rates. Few, indeed, can be so ill informed, as not to know, that these two topics, for many years, were involved in the "Free Trade" and "Protective Tariff" doctrines, and afforded the _materiel_ of the political contests between the North and the South--between free labor and slave labor. A very brief notice of the history of that controversy, will demonstrate the truth of this assertion. The attempt of the agricultural States, thirty years since, to establish the protective policy, and promote "Domestic Manufactures," was a struggle to create such a division of labor as would afford a "Home Market" for their products, no longer in demand abroad. The first decisive action on the question, by Congress, was in 1824; when the distress in these States, and the measures proposed for their relief, by national legislation, were discussed on the passage of the "Tariff Bill" of that year. The ablest men in the nation were engaged in the controversy. As provisions are the most important item on the one hand, and cotton on the other, we shall use these two terms as the representatives of the two classes of products, belonging, respectively, to free labor and to slave labor.