Impeachment history in brief form here today.
Federalist Paper #65, written by my favorite Founding Father, Alexander Hamilton, outlines some of the reasoning and thinking behind the establishment of the Senate, presided over by the Cheif Justice, as the jury, requiring a two-thirds majority to convict, and the House, as the prosecutor, requiring a simple majority to present the evidence. Ponder the words.
In many cases it will connect itself with the pre-existing factions, and will enlist all their animosities, partialities, influence, and interest on one side or on the other; and in such cases there will always be the greatest danger that the decision will be regulated more by the comparative strength of parties, than by the real demonstrations of innocence or guilt.
The delicacy and magnitude of a trust which so deeply concerns the political reputation and existence of every man engaged in the administration of public affairs, speak for themselves. The difficulty of placing it rightly, in a government resting entirely on the basis of periodical elections, will as readily be perceived, when it is considered that the most conspicuous characters in it will, from that circumstance, be too often the leaders or the tools of the most cunning or the most numerous faction, and on this account, can hardly be expected to possess the requisite neutrality towards those whose conduct may be the subject of scrutiny.