There are also two kinds of truths: truth of reasoning and truths of fact. Truths of reasoning are necessary and their opposite is impossible; those of fact are contingent and their opposite is possible.
-- Gottfried Leibniz
   
Gottfried Leibniz   Name:
Gottfried Leibniz
Type:
Philosopher
Nationality:
German
https://www.nutquote.com/quote/Gottfried_Leibniz