"I was not sure but that it was all royal chaff, till I made my way back south to the head-waters again, and had the natives of the islet Mpabala slowly moving the hands all around the great expanse, with 183° of sea horizon, and saying that is Chambeze, forming the great Bangweolo, and disappearing behind that western headland to change its name to Luapula, and run down past Cazembe to Moero. That was the moment of discovery, and not my passage or the Portuguese passage of the river. If, however, any one chooses to claim for them the discovery of Chambeze as one line of drainage of the Nile Valley, I shall not fight with him; Culpepper's astrology was in the same way the forerunner of the Herschels' and the other astronomers that followed."
To another old friend, Mr. James Young, he wrote about the same time: "_Opere peracto ludemus_--the work being finished, we will play--you remember in your Latin Rudiments lang syne. It is true for you, and I rejoice to think it is now your portion, after working nobly, to play. May you have a long spell of it! I am differently situated; I shall never be able to play.... To me it seems to be said, 'If thou forbear to deliver them that are drawn unto death, and those that be ready to be slain; if thou sayest, Behold we knew it not, doth not He that pondereth the heart consider, and He that keepeth thy soul doth He not know, and shall He not give to every one according to his works?' I have been led, unwittingly, into the slaving field of the Banians and Arabs in Central Africa. I have seen the woes inflicted, and I must still work and do all I can to expose and mitigate the evils. Though hard work is still to be my lot, I look genially on others more favored in their lot. I would not be a member of the 'International,' for I love to see and think of others enjoying life.
"During a large part of this journey I had a strong presentiment that I should never live to finish it. It is weakened now, as I seem to see the end toward which I have been striving looming in the distance. This presentiment did not interfere with the performance of any duty; it only made me think a great deal more of the future state of being."
In his latest letters there is abundant evidence that the great desire of his heart was to expose the slave-trade, rouse public feeling, and get that great hindrance to all good for ever swept away.
"Spare no pains," he wrote to Dr. Kirk in 1871, "in attempting to persuade your superior to this end, and the Divine blessing will descend on you and yours."
To his daughter Agnes he wrote (15th August, 1872): "No one can estimate the amount of God-pleasing good that will be done, if, by Divine favor, this awful slave-trade, into the midst of which I have come, be abolished. This will be something to have lived for, and the conviction has grown in my mind that it was _for this end_ I have been detained so long."
To his brother in Canada he says (December, 1872): "If the good Lord permits me to put a stop to the enormous evils of the inland slave-trade, I shall not grudge my hunger and toils. I shall bless his name with all my heart. The Nile sources are valuable to me only as a means of enabling me to open my mouth with power among men. It is this power I hope to apply to remedy an enormous evil, and join my poor little helping hand in the enormous revolution that in his all-embracing Providence He has been carrying on for ages, and is now actually helping forward. Men may think I covet fame, but I make it a rule never to read aught written in my praise."