What can we learn today from the moral teachings of the great Greek philosophers Plato and Aristotle? Actually, quite a lot, especially about ourselves!
Would you like a landscape by Hitler hanging on your wall, even if it was great art? Or, can we define or devalue a work of art according to its history?
Does God really exist? Leibniz believed he could prove there was a God through a process of pure reason, but his was an a God of the intellect rather than a God found in the Old or New Testaments, and other thinkers had different ideas.
A master of Metaphysics, Leibniz believed every part of your body has a soul, although your dominant soul is the boss. This allows you to have free will, just as God has free will.
Voltaire upheld reason over ignorance, tolerance over bigotry and religious superstition, and caused mayhem and discord amongst his fellow philosophers and the Establishment.