The following is from the Toronto Leader of April 18 — Lengthy though the reports connected with the assas sination of Mr Lincoln have been, there has not been a word stated, either by way of suggestion or as a matter of fact, as 'to the motive which could have impelled John Wilkes Booth to brace himself to the fearful work of striking down, in the height of his exultation over the victories of the past few months, the President of the United States. Surely something must have been known of the man by the authorities at Washington, where he had spent so much of his life. Was there no' acto'f the Government whose effect could be traced in any way to Booth? The reports hint not a word; but the deficiency is supplied by the Buffalo Courier of yesterday. It says — 'the motives which impelled the assassin to his in fernal work seem to lie chie?y on the surface. 'w'e are assured by a gentleman who claims to have positive knowledge on the subj'ett, that Booth is' an own ecusin of the 'rebel Captain Beall, who was executed a few weeks since on Governor's Island.' And it adds Most clearly, we think, the inspiration of the murder came not from the conquered and; prostrate South, but was wrought up in the secret chambers of a mind partially prepared for the evil work by its recklessness, desperate nature, and its bitter hatreds, and finally impelled to the act by the mad promptings of personal revenge.' If this should prove to be true, 'it will be a singular instance of the remarkable agreement of popular apprehension with established fact. Hardly had the news of the'assassina tion'becom'e [known here 'than thosé' who endeavour to find a cause for the horrible deed had their minds directed to,t'he execution of Captain Beall. This brave man, be fore heldied, declared that his death Would be avenged, and Booth is reported to have uttered the words, 'sic semper tyrannis,' to have also said, I am avenged,' or, as some accounts have it, the South is avenged.'