But we have yet stronger evidence. The total abolishment of slavery in the southern republics has proved beyond dispute the safety and utility of immediate abolition. The departed Bolivar indeed deserves his glorious title of Liberator, for he began his career of freedom by striking off the fetters of his own slaves, seven hundred in number. In an official letter from the Mexican Envoy of the British Government, dated Mexico, March, 1826, and addressed 'to the Right Hon. George Canning, the superiority of free over slave labor is clearly demonstrated by the following facts:-- 2. It is now carried on exclusively by the labor of free blacks. 3. It was formerly wholly sustained by the forced labor of slaves, purchased at Vera Cruz at $300 to $400 each. 4. Abolition in this section was effected not by governmental interference, not even from motives of humanity, but from an irresistible conviction on the part of the planters that their pecuniary interest demanded it. 5. The result has proved the entire correctness of this conviction; and the planters would now be as unwilling as the blacks themselves to return to the old system. Let our Southern brethren imitate this example. It is in vain, in the face of facts like these, to talk of the necessity of maintaining the abominable system, operating as it does like a double curse upon planters and slaves. Heaven and earth deny its necessity. It is as necessary as other robberies, and no more. Yes, putting aside altogether the righteous law of the living God--the same yesterday, to-day, and forever--and shutting out the clearest political truths ever taught by man, still, in human policy selfish expediency would demand of the planter the immediate emancipation of his slaves. Because slave labor is the labor of mere machines; a mechanical impulse of body and limb, with which the mind of the laborer has no sympathy, and from which it constantly and loathingly revolts. Because slave labor deprives the master altogether of the incalculable benefit of the negro's will. That does not cooperate with the forced toil of the body. This is but the necessary consequence of all labor which does not benefit the laborer. It is a just remark of that profound political economist, Adam Smith, that "a slave can have no other interest than to eat and waste as much, and work as little, as he can." To my mind, in the wasteful and blighting influences of slave labor there is a solemn and warning moral.