David was inspired by the description of "smoke from a thousand villages" in central Africa where the Gospel and civilized commerce were unknown. He determined to become a missionary also.

He joined Dr. Moffat at Cape Town under the auspices of the London Missionary Society. There he married Moffat's daughter, Mary. She bore him three sons and two daughters before returning to London to escape the debilitating effects of malaria.

Livingstone severed his relationship with the Missionary Society in 1857 to accept the position of British consul at Quelimane. In this capacity he explored central Africa extensively to map the rivers. He believed the waterways were key to civilized development.

The trade in slaves by Arabs -- and compliant African chiefs -- was an "abomination" he sought to eradicate.

During a visit to England to receive instructions for his consular duties, Livingstone was given the Freedom of the City of Edinburgh. In a testimonial speech, the shy recipient spoke about the evils of slavery:

"In going back [to Africa], my object is to try and get a permanent path into the central region, from which most of the slaves have always been drawn." said Dr. Livingstone.

"The native slave-drivers go into the country and carry our manufactures there. With a few yards of cloth they purchase slaves. Then, they take them to the seacoast. The people are so anxious to get a little of our manufactures that, in return for them, they part not with their own children, but with children kidnapped from other tribes.

"I hope to be able to make a path by the Zambezi River into the central country. Then, if we can supply the people with our goods for lawful commerce, I think we have a fair prospect of putting a stop to the slave trade.

"We know that our own country is dependent in a great measure for its supply of cotton upon the United States. Thus, we are dependent for this material upon slave labor.

"If we get abundant supplies of raw material from Africa, we shall soon find that the slave-holders in America will become more enlightened."

Ironically, and sadly, the Livingstone's oldest son, Robert, lost his life in the American Civil War.