Reality cannot be found except in One single source, because of the interconnection of all things with one another.
Gottfried LeibnizThere are also two kinds of truths, those of reasoning and those of fact. Truths of reasoning are necessary and their opposite is impossible, and those of fact are contingent and their opposite is possible. When a truth is necessary its reason can be found by analysis, resolving it into more simple ideas and truths until we reach those which are primitive.
Gottfried Leibniz