User blog comment:The Milkman/Mass Effect in Retrospect/@comment-173.189.226.12-20130418023302/@comment-5267262-20130418143559

The catalyst's purpose was to preserve life at all cost. It understood that as organic life in general not of any one particular species. It came to the conclusion that it needed to protect them from what they could end up creating. That is why the leviathans say that the catalyst's job is not finished. So long as there is life that could make something to endanger itself and everything else it is not finished. Would it help you that much if the catalyst brings out a list that goes species a created synthetics b species a was destroyed by synthetics b species c created synthetics d, species c was destroyed by synthetics d. etc Because that is about as much context as you would be able to get if they tried to give evidence. The evidence the catalyst would have used to come to its conclusions would be so far history that it would add nothing. Like it said when you ask about who first made the crucible "you would not know them and there is not enough time to explain" (your fleet is still getting mashed out there)